The challenge of transitioning from temporary humanitarian settlements to more sustainable human settlements is due to a significant increase in the number of forcibly displaced people over recent decades, difficultie...The challenge of transitioning from temporary humanitarian settlements to more sustainable human settlements is due to a significant increase in the number of forcibly displaced people over recent decades, difficulties in providing social services that meet the required standards, and the prolongation of emergencies. Despite this challenging context, short-term considerations continue to guide their planning and management rather than more integrated, longer-term perspectives, thus preventing viable, sustainable development. Over the years, the design of humanitarian settlements has not been adapted to local contexts and perspectives, nor to the dynamics of urbanization and population growth and data. In addition, the current approach to temporary settlement harms the environment and can strain limited resources. Inefficient land use and ad hoc development models have compounded difficulties and generated new challenges. As a result, living conditions in settlements have deteriorated over the last few decades and continue to pose new challenges. The stakes are such that major shortcomings have emerged along the way, leading to disruption, budget overruns in a context marked by a steady decline in funding. However, some attempts have been made to shift towards more sustainable approaches, but these have mainly focused on vague, sector-oriented themes, failing to consider systematic and integration views. This study is a contribution in addressing these shortcomings by designing a model-driving solution, emphasizing an integrated system conceptualized as a system of systems. This paper proposes a new methodology for designing an integrated and sustainable human settlement model, based on Model-Based Systems Engineering and a Systems Modeling Language to provide valuable insights toward sustainable solutions for displaced populations aligning with the United Nations 2030 agenda for sustainable development.展开更多
The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limi...The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern space.The entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each other.Particularly,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion system.This study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle contour.Most existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow field.However,research has yet to implement an integrated,optimal design of the section from the rotor to the nozzle.Given the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the findings.This program used an existing model as the design case.This study referred to the actual trial data as the design conditions for the proposed model.Unlike prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational domain.After the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual condition.Based on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be linear.Furthermore,for the pump head,static pressure had a more significant impact than dynamic pressure.展开更多
Refugee settlements face several challenges in transitioning from a temporary planning approach to more sustainable settlements. This is mainly due to an increase in the number of forcibly displaced people over the la...Refugee settlements face several challenges in transitioning from a temporary planning approach to more sustainable settlements. This is mainly due to an increase in the number of forcibly displaced people over the last few decades, and the difficulties of sustainably providing social services that meet the required standards. The development of refugee settlements assumed that forcibly displaced people would return to their places or countries of origin. Unfortunately, displacement situations are prolonged indefinitely, forcing these people to spend most of their lives in conditions that are often deplorable and substandard, and therefore unsustainable. In most cases, the establishment of refugee settlements is triggered by an emergency caused by an influx of forcibly displaced people, who need to be accommodated urgently and provided with some form of international assistance and protection. This leaves little or no time for proper planning for long-term development as required. In addition, the current approach to temporary settlement harms the environment and can strain limited resources with ad hoc development models that have exacerbated difficulties. As a result, living conditions in refugee settlements have deteriorated over the last few decades and continue to pose challenges as to how best to design, plan, and sustain settlements over time. To contribute to addressing these challenges, this study proposes a new methodology supported by Model-Based Systems Engineering (MBSE) and a Systems Modeling Language (SysML) to develop a typical sustainable human settlement system model, which has functionally and operationally executed using a Systems Engineering (SE) approach. To assess the sustainability capacity of the proposed system, this work applies a matrix of crossed impact multiplication through a case study by conducting a system capacity interdependence analysis (SCIA) using the MICMAC methodology (Cross-impact matrix multiplication applied to classification) to assess the interdependency that exist between the sub-systems categories to deliver services at the system level. The sustainability analysis results based on capacity variables influence and dependency models shows that development activities in the settlement are unstable and, therefore, unsustainable since there is no apparent difference between the influential and dependent data used for the assessment. These results illustrate that an integrated system could improve human settlements’ sustainability and that capacity building in service delivery is beneficial and necessary.展开更多
Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier scheme used in modern broadband wireless communication systems to transmit data over a number of orthogonal subcarriers. When transmitted signals ar...Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier scheme used in modern broadband wireless communication systems to transmit data over a number of orthogonal subcarriers. When transmitted signals arrive at the receiver by more than one path of different length, the received signals are staggered in time;this is multipath propagation. To mitigate the effect of dispersed channel distortion caused by random channel delay spread, Cyclic Prefix (CP) is introduced to eliminate Inter-Symbol Interference (ISI). In the literature, researchers have focused on carrying out investigations (or studies) mainly on the two existing CP insertions, namely: normal and extended CPs. Both CPs have limitations with respect to handling channel delay spreads. In the current work, a new CP, herein referred to as “ultra extended” CP is proposed to address delay spreads beyond the limits of the normal and extended CPs. The efficacy of the proposed ultra extended CP is tested via simulation under different scenarios. It is shown by the results obtained that the proposed CP can efficiently handle delay spreads beyond the limits of the existing normal and extended CP, and can indeed be implemented in the design of future telecommunication systems to accommodate higher channel delay spreads and it ensures wider cell coverage.展开更多
Military object detection and identification is a key capability in surveillance and reconnaissance.It is a major factor in warfare effectiveness and warfighter survivability.Inexpensive,portable,and rapidly deployabl...Military object detection and identification is a key capability in surveillance and reconnaissance.It is a major factor in warfare effectiveness and warfighter survivability.Inexpensive,portable,and rapidly deployable small unmanned aerial systems(s UAS)in conjunction with powerful deep learning(DL)based object detection models are expected to play an important role for this application.To prove overall feasibility of this approach,this paper discusses some aspects of designing and testing of an automated detection system to locate and identify small firearms left at the training range or at the battlefield.Such a system is envisioned to involve an s UAS equipped with a modern electro-optical(EO)sensor and relying on a trained convolutional neural network(CNN).Previous study by the authors devoted to finding projectiles on the ground revealed certain challenges such as small object size,changes in aspect ratio and image scale,motion blur,occlusion,and camouflage.This study attempts to deal with these challenges in a realistic operational scenario and go further by not only detecting different types of firearms but also classifying them into different categories.This study used a YOLOv2CNN(Res Net-50 backbone network)to train the model with ground truth data and demonstrated a high mean average precision(m AP)of 0.97 to detect and identify not only small pistols but also partially occluded rifles.展开更多
Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an ...Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an aerosol test chamber are required to examine factors of contamination, decontamination, and cross-contamination. This study presents the design, construction, and a method for characterizing an aerosol test chamber for a full-sized manikin on a standard North Atlantic Treaty Organization litter. The methodology combined air velocity measurements, aerosol particle counts and size distributions, and computational fluid dynamics modeling to describe the chamber’s performance in three dimensions. This detailed characterization facilitates future experimental design by predicting chamber performance for a variety of patient-focused research.展开更多
Given the challenges facing most humanitarian operations worldwide, a change of approach is needed to ensure greater sustainability of humanitarian settlements right from the planning stage. Some studies attribute uns...Given the challenges facing most humanitarian operations worldwide, a change of approach is needed to ensure greater sustainability of humanitarian settlements right from the planning stage. Some studies attribute unsustainability to inadequate provision of basic resources and highlight the apparent bottlenecks that prevent access to the meaningful data needed to plan and remedy problems. Most operations have relied on an “ad hoc ism” approach, employing parallel and disconnected data processing methods, resulting in a wide range of data being collected without subsequent prioritization to optimize interconnections that could enhance performance. There have been little efforts to study the trade-offs potentially at stake. This work proposes a new framework enabling all subsystems to operate in a single system and focusing on data processing perspective. To achieve this, this paper proposes a Triple Nexus Framework as an attempt to integrate water, energy, and housing sector data derived from a specific sub-system within the overall system in the application of Model-Based Systems Engineering. Understanding the synergies between water, energy, and housing, Systems Engineering characterizes the triple nexus framework and identifies opportunities for improved decision-making in processing operational data from these sectors. Two scenarios illustrate how an integrated platform could be a gateway to access meaningful operational data in the system and a starting point for modeling integrated human settlement systems. Upon execution, the model is tested for nexus megadata processing, and the optimization simulation yielded 67% satisfactory results, demonstrating that an integrated system could improve sustainability, and that capacity building in service delivery is more than beneficial.展开更多
To improve the productivity of cluster tools in semiconductor fabrications,on the basis of stating scheduling problems,a try and error-based scheduling algorithm was proposed with residency time constraints and an obj...To improve the productivity of cluster tools in semiconductor fabrications,on the basis of stating scheduling problems,a try and error-based scheduling algorithm was proposed with residency time constraints and an objective of minimizing Makespan for the wafer jobs in cluster tools.Firstly,mathematical formulations of scheduling problems were presented by using assumptions and definitions of a scheduling domain.Resource conflicts were analyzed in the built scheduling model,and policies to solve resource conflicts were built.A scheduling algorithm was developed.Finally,the performances of the proposed algorithm were evaluated and compared with those of other methods by simulations.Experiment results indicate that the proposed algorithm is effective and practical in solving the scheduling problem of the cluster tools.展开更多
This study aims to reduce the work-affected layer of the machined surface by carrying out the grinding at the speed over static pr o pagation speed of plastic wave of ductile materials and also aims to clarify suc h s...This study aims to reduce the work-affected layer of the machined surface by carrying out the grinding at the speed over static pr o pagation speed of plastic wave of ductile materials and also aims to clarify suc h super high-speed machining mechanism.This paper reports on the result obtain ed through the molecular dynamics simulations and experiments on the super-spee d grinding below and beyond static propagation speed of aluminum.From the simul ation results,it is verified that the plastic deformation is reduced when the m a chining speed exceeds the material static propagation speed of plastic wave and its mechanism is completely different from that of the ordinary grinding process .Experimental results also show the improvement of the surface integrity when t he machining speed exceeds the material static propagation speed of plastic wave .展开更多
The main objective of this research is to study the effect of rib arrangement on the distributions of the local heat transfer coefficient in a stationary channel. In this study, the ribs with square cross section were...The main objective of this research is to study the effect of rib arrangement on the distributions of the local heat transfer coefficient in a stationary channel. In this study, the ribs with square cross section were used to place on two side walls for study. The rib height-to-hydraulic diameter ratio(e/Dh) and the rib pitchto-height(p/e) ratio were fixed at 0.133 and 10, respectively. Three different types of rib arrangement for inclined ribs, V-shaped ribs and inverted V-shaped ribs were investigated. The rib angle of attack(α)was varied from 30?to 90?for inclined ribs and 45?and 60?for both V-shaped and inverted V-shaped ribs, and compared at constant Reynolds number Re =30000. Thermal Liquid Crystal sheet was applied for evaluating the heat transfer distributions. The results showed that the average Nusselt number on surface with rib inclined angle at 60?, 45?, and 60?V-shaped ribs was improved up to about 20%, 25% and 30%higher than case of angle 90?and the rib inclined angle at 60?V-shaped ribs provided the highest Nusselt number covering largest area when compared to the other cases.展开更多
An optimal replacement model for gamma deteriorating systems is studied.This methodology uses a gamma distribution to model the material degradation,and the impact of imperfect maintenance actions on the system reliab...An optimal replacement model for gamma deteriorating systems is studied.This methodology uses a gamma distribution to model the material degradation,and the impact of imperfect maintenance actions on the system reliability is investigated.The state of a degrading system immediately after the imperfect maintenance action is assumed as a random variable and the maintenance time follows a geometric process.A maintenance policy(N) is applied by which the system will be repaired whenever it experiences Nth preventive maintenance(PM),and an optimal policy(N) could be determined numerically or analytically for minimizing the long-run average cost per unit time.Finally,a numerical example is presented to demonstrate the use of this policy.展开更多
In the optimal control problem of nonlinear dynamical system,the Hamiltonian formulation is useful and powerful to solve an optimal control force.However,the resulting Euler-Lagrange equations are not easy to solve,wh...In the optimal control problem of nonlinear dynamical system,the Hamiltonian formulation is useful and powerful to solve an optimal control force.However,the resulting Euler-Lagrange equations are not easy to solve,when the performance index is complicated,because one may encounter a two-point boundary value problem of nonlinear differential algebraic equations.To be a numerical method,it is hard to exactly preserve all the specified conditions,which might deteriorate the accuracy of numerical solution.With this in mind,we develop a novel algorithm to find the solution of the optimal control problem of nonlinear Duffing oscillator,which can exactly satisfy all the required conditions for the minimality of the performance index.A new idea of shape functions method(SFM)is introduced,from which we can transform the optimal control problems to the initial value problems for the new variables,whose initial values are given arbitrarily,and meanwhile the terminal values are determined iteratively.Numerical examples confirm the high-performance of the iterative algorithms based on the SFM,which are convergence fast,and also provide very accurate solutions.The new algorithm is robust,even large noise is imposed on the input data.展开更多
Possessing the unique and highly valuable properties, graphene sheets(GSs) have attracted increasing attention including that from the building engineer due to the fact that Graphene can be utilized to reinforce concr...Possessing the unique and highly valuable properties, graphene sheets(GSs) have attracted increasing attention including that from the building engineer due to the fact that Graphene can be utilized to reinforce concrete and other building materials. In this work, the nonlocal elastic theory and classical plate theory(CLPT) are used to derive the governing equations. The element-free framework for analyzing the buckling behaviors of double layer circular graphene sheets(DLCGSs) relying on an elastic medium is proposed. Pasternak-type model is adopted to describe the elastic medium. Accordingly, the influences of boundary conditions, size of GSs and nonlocal parameters on the buckling behavior of DLCGSs are investigated. The results show that the OP buckling modes are only sensible to the van der Waals forces.展开更多
Numerical simulation of antennae is a topic in computational electromagnetism,which is concerned withthe numerical study of Maxwell equations.By discrete exterior calculus and the lattice gauge theory with coefficient...Numerical simulation of antennae is a topic in computational electromagnetism,which is concerned withthe numerical study of Maxwell equations.By discrete exterior calculus and the lattice gauge theory with coefficient R,we obtain the Bianchi identity on prism lattice.By defining an inner product of discrete differential forms,we derivethe source equation and continuity equation.Those equations compose the discrete Maxwell equations in vacuum caseon discrete manifold,which are implemented on Java development platform to simulate the Gaussian pulse radiation onantennaes.展开更多
In this paper,a decentralized proportional-derivative(PD)controller design for non-uniform motion of a Hamiltonian hybrid system is considered.A Hamiltonian hybrid system with the capability of producing a non-uniform...In this paper,a decentralized proportional-derivative(PD)controller design for non-uniform motion of a Hamiltonian hybrid system is considered.A Hamiltonian hybrid system with the capability of producing a non-uniform motion is developed. The structural properties of the system are investigated by means of the theory of Harniltonian systems.A relationship between the parameters of the system and the parameters of the proposed decentralized PD controller is shown to ensure local stability and tracking performance.Simulation results are included to show the obtained non-uniform motion.展开更多
Economic wood processing employs the use of industrial machines for cutting,shaping,milling,and sawing timber,thereby leading to the generation of high levels of noise.Published data from empirical studies have catego...Economic wood processing employs the use of industrial machines for cutting,shaping,milling,and sawing timber,thereby leading to the generation of high levels of noise.Published data from empirical studies have categorized noise as an environmental hazard of global significance.Furthermore,noise exposure limits for different industries and all the industrial machines available has not been formally established as it presently exists in developed nations around the world.Therefore,this study assessed the daily exposure of sawmills workers to noise in Southwestern Nigeria.Reconnaissance surveys were first carried out in Osun,Oyo,Ondo,Ekiti,Lagos,and Ogun States to select sawmills that were fully operational and fit for the study.Two fully functional sawmills in two cities of each State were eventually selected for data collection,making a total of 24 sawmills,while the Circular Machines(CM),Planer Machines(PM),and Band-saw Machines(BM)were the machines in each sawmill considered.Two machines each of CM,PM,and BM were considered in each sawmill,making a total of forty-eight(48)machines each of CM,PM,and BM.Sound data were collected between 7 am and 7 pm each day for six days(between Monday and Saturday)using Extech 407732 sound level meter and all stabilized measurements were taken three times at different intervals.The data collected were in three different periods:Machine No-work Period(NPm),Machine Idle Period(IPm),and Machine Working Period(WPm).A two–way Analysis of Variance(ANOVA)was carried out at P<0.05 to determine whether there is a significant difference in the sound level average before and after the break,for both the idle and working periods of the three machines considered.This was also done to determine whether there is a signifi-cant difference between the sound level average of the results collected during idle and working periods of the three machines.Noise Pollution Levels(Lnp)ranged from 83.20 dB(PM)to 107.65(BM)and 93.42(CM and PM)–116.00(BM)respectively,while IPm also gave the least noise pollution level of 95.79 dB and WPm gave the highest level of 102.88 dB.The results revealed that all the machines’Lnp values in the working period are more than the 90 dB acceptable limit the recommendation value of 90 dB while 89.6%of CMs,75%of PMs,and 89.6%of BM had their Lnp above 90 dB in the idle period respectively.The minimum and the maximum noise dose levels for IPm,WPm and overall are 0.09(BM)and 2.37(CM),0.50(CM),and 4.77(PM)and 0.69(BM)and 6.64(PM)respectively.The study found out that the fundamental contributing factors to the high noise levels in sawmills are poor machine maintenance,use of old and obsolete machines,poor housekeeping strategy,limited space,workers’negligence,lack of PPE,and lack of occupational safety training.The study recommends that proper workplace practices such as use of personal protective equipment,new and modern machines,training,and occupational safety programmes be implemented in the considered sawmills.展开更多
This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility sys...This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility systems are also increasing,but the railroad electrical facility system in Korea is rapidly aging.To solve this problem,various methodologies are applied to ensure operational reliability and stability for railroad electrical facility systems,but there is a lack of detailed evaluation criteria for railroad electrical facility system maintenance.Also,maintenance items must be selected in a scientific and systematic method.Therefore,railroad electrical facility systems are selected for study.Design StructureMatrix(DSM)is utilized to establish considerations tailored to the maintenance characteristics,and the Fuzzy-TOPSIS methodology is utilized for determining the maintenance detail evaluation item baseline weights,a multi-criteria decision-making problem.Studies show that degradation,insulation items have the highest weight of 14.63%,and capacity items have the lowest weight of 5.34%.The results of this may be contributed to the underlying research in carrying out maintenance activities to ensure the reliability and safety of railroad electrical facility systems.展开更多
Effect of viscosity on flow patterns of pumping-up of liquid generated by a cone rotating at the liquid surface has been experimentally studied with various concentrations of glycerol aqueous solution. We have previou...Effect of viscosity on flow patterns of pumping-up of liquid generated by a cone rotating at the liquid surface has been experimentally studied with various concentrations of glycerol aqueous solution. We have previously found that the higher viscous non-Newtonian fluid was lifted-up along the conical surface with a radial filament-wise pattern, which is quite different from the monotonic thin film-wise pattern observed for the lower viscous fluid such as water. In order to elucidate the pumping-up mechanism, a transition diagram indicating the critical rotation rate is obtained as a function of viscosity?of Newtonian fluid in this study, varying from the lower value of water (μ?=?0.890 mPa·s) to the higher one of glycerin (μ?= 910?mPa·s). It is found that there are three categories depending on the viscosity classified as?1) film-wise pumping-up region for the viscosity?μ?≤?134?mPa·s,?2) filament-wise pumping-up one for the viscosity?μ?≥?520?mPa·s, and?3) no pumping-up phenomenon occurs?for 134??μ??mPa·s.展开更多
文摘The challenge of transitioning from temporary humanitarian settlements to more sustainable human settlements is due to a significant increase in the number of forcibly displaced people over recent decades, difficulties in providing social services that meet the required standards, and the prolongation of emergencies. Despite this challenging context, short-term considerations continue to guide their planning and management rather than more integrated, longer-term perspectives, thus preventing viable, sustainable development. Over the years, the design of humanitarian settlements has not been adapted to local contexts and perspectives, nor to the dynamics of urbanization and population growth and data. In addition, the current approach to temporary settlement harms the environment and can strain limited resources. Inefficient land use and ad hoc development models have compounded difficulties and generated new challenges. As a result, living conditions in settlements have deteriorated over the last few decades and continue to pose new challenges. The stakes are such that major shortcomings have emerged along the way, leading to disruption, budget overruns in a context marked by a steady decline in funding. However, some attempts have been made to shift towards more sustainable approaches, but these have mainly focused on vague, sector-oriented themes, failing to consider systematic and integration views. This study is a contribution in addressing these shortcomings by designing a model-driving solution, emphasizing an integrated system conceptualized as a system of systems. This paper proposes a new methodology for designing an integrated and sustainable human settlement model, based on Model-Based Systems Engineering and a Systems Modeling Language to provide valuable insights toward sustainable solutions for displaced populations aligning with the United Nations 2030 agenda for sustainable development.
基金the financial support from the National Science and Technology Council,Taiwan(Grant No.MOST 111-2221-E-019-035-).
文摘The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern space.The entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each other.Particularly,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion system.This study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle contour.Most existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow field.However,research has yet to implement an integrated,optimal design of the section from the rotor to the nozzle.Given the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the findings.This program used an existing model as the design case.This study referred to the actual trial data as the design conditions for the proposed model.Unlike prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational domain.After the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual condition.Based on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be linear.Furthermore,for the pump head,static pressure had a more significant impact than dynamic pressure.
文摘Refugee settlements face several challenges in transitioning from a temporary planning approach to more sustainable settlements. This is mainly due to an increase in the number of forcibly displaced people over the last few decades, and the difficulties of sustainably providing social services that meet the required standards. The development of refugee settlements assumed that forcibly displaced people would return to their places or countries of origin. Unfortunately, displacement situations are prolonged indefinitely, forcing these people to spend most of their lives in conditions that are often deplorable and substandard, and therefore unsustainable. In most cases, the establishment of refugee settlements is triggered by an emergency caused by an influx of forcibly displaced people, who need to be accommodated urgently and provided with some form of international assistance and protection. This leaves little or no time for proper planning for long-term development as required. In addition, the current approach to temporary settlement harms the environment and can strain limited resources with ad hoc development models that have exacerbated difficulties. As a result, living conditions in refugee settlements have deteriorated over the last few decades and continue to pose challenges as to how best to design, plan, and sustain settlements over time. To contribute to addressing these challenges, this study proposes a new methodology supported by Model-Based Systems Engineering (MBSE) and a Systems Modeling Language (SysML) to develop a typical sustainable human settlement system model, which has functionally and operationally executed using a Systems Engineering (SE) approach. To assess the sustainability capacity of the proposed system, this work applies a matrix of crossed impact multiplication through a case study by conducting a system capacity interdependence analysis (SCIA) using the MICMAC methodology (Cross-impact matrix multiplication applied to classification) to assess the interdependency that exist between the sub-systems categories to deliver services at the system level. The sustainability analysis results based on capacity variables influence and dependency models shows that development activities in the settlement are unstable and, therefore, unsustainable since there is no apparent difference between the influential and dependent data used for the assessment. These results illustrate that an integrated system could improve human settlements’ sustainability and that capacity building in service delivery is beneficial and necessary.
文摘Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier scheme used in modern broadband wireless communication systems to transmit data over a number of orthogonal subcarriers. When transmitted signals arrive at the receiver by more than one path of different length, the received signals are staggered in time;this is multipath propagation. To mitigate the effect of dispersed channel distortion caused by random channel delay spread, Cyclic Prefix (CP) is introduced to eliminate Inter-Symbol Interference (ISI). In the literature, researchers have focused on carrying out investigations (or studies) mainly on the two existing CP insertions, namely: normal and extended CPs. Both CPs have limitations with respect to handling channel delay spreads. In the current work, a new CP, herein referred to as “ultra extended” CP is proposed to address delay spreads beyond the limits of the normal and extended CPs. The efficacy of the proposed ultra extended CP is tested via simulation under different scenarios. It is shown by the results obtained that the proposed CP can efficiently handle delay spreads beyond the limits of the existing normal and extended CP, and can indeed be implemented in the design of future telecommunication systems to accommodate higher channel delay spreads and it ensures wider cell coverage.
文摘Military object detection and identification is a key capability in surveillance and reconnaissance.It is a major factor in warfare effectiveness and warfighter survivability.Inexpensive,portable,and rapidly deployable small unmanned aerial systems(s UAS)in conjunction with powerful deep learning(DL)based object detection models are expected to play an important role for this application.To prove overall feasibility of this approach,this paper discusses some aspects of designing and testing of an automated detection system to locate and identify small firearms left at the training range or at the battlefield.Such a system is envisioned to involve an s UAS equipped with a modern electro-optical(EO)sensor and relying on a trained convolutional neural network(CNN).Previous study by the authors devoted to finding projectiles on the ground revealed certain challenges such as small object size,changes in aspect ratio and image scale,motion blur,occlusion,and camouflage.This study attempts to deal with these challenges in a realistic operational scenario and go further by not only detecting different types of firearms but also classifying them into different categories.This study used a YOLOv2CNN(Res Net-50 backbone network)to train the model with ground truth data and demonstrated a high mean average precision(m AP)of 0.97 to detect and identify not only small pistols but also partially occluded rifles.
文摘Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an aerosol test chamber are required to examine factors of contamination, decontamination, and cross-contamination. This study presents the design, construction, and a method for characterizing an aerosol test chamber for a full-sized manikin on a standard North Atlantic Treaty Organization litter. The methodology combined air velocity measurements, aerosol particle counts and size distributions, and computational fluid dynamics modeling to describe the chamber’s performance in three dimensions. This detailed characterization facilitates future experimental design by predicting chamber performance for a variety of patient-focused research.
文摘Given the challenges facing most humanitarian operations worldwide, a change of approach is needed to ensure greater sustainability of humanitarian settlements right from the planning stage. Some studies attribute unsustainability to inadequate provision of basic resources and highlight the apparent bottlenecks that prevent access to the meaningful data needed to plan and remedy problems. Most operations have relied on an “ad hoc ism” approach, employing parallel and disconnected data processing methods, resulting in a wide range of data being collected without subsequent prioritization to optimize interconnections that could enhance performance. There have been little efforts to study the trade-offs potentially at stake. This work proposes a new framework enabling all subsystems to operate in a single system and focusing on data processing perspective. To achieve this, this paper proposes a Triple Nexus Framework as an attempt to integrate water, energy, and housing sector data derived from a specific sub-system within the overall system in the application of Model-Based Systems Engineering. Understanding the synergies between water, energy, and housing, Systems Engineering characterizes the triple nexus framework and identifies opportunities for improved decision-making in processing operational data from these sectors. Two scenarios illustrate how an integrated platform could be a gateway to access meaningful operational data in the system and a starting point for modeling integrated human settlement systems. Upon execution, the model is tested for nexus megadata processing, and the optimization simulation yielded 67% satisfactory results, demonstrating that an integrated system could improve sustainability, and that capacity building in service delivery is more than beneficial.
基金This project is supported by National Hi-Tech Research and Development Program of China(863 Program, No.2001AA422360) Chinese Academy of Sciences Advanced Manufacturing Technology R&D Base Foundation, Chrna(No.F000112).
基金Projects(71071115,60574054) supported by the National Natural Science Foundation of China
文摘To improve the productivity of cluster tools in semiconductor fabrications,on the basis of stating scheduling problems,a try and error-based scheduling algorithm was proposed with residency time constraints and an objective of minimizing Makespan for the wafer jobs in cluster tools.Firstly,mathematical formulations of scheduling problems were presented by using assumptions and definitions of a scheduling domain.Resource conflicts were analyzed in the built scheduling model,and policies to solve resource conflicts were built.A scheduling algorithm was developed.Finally,the performances of the proposed algorithm were evaluated and compared with those of other methods by simulations.Experiment results indicate that the proposed algorithm is effective and practical in solving the scheduling problem of the cluster tools.
文摘This study aims to reduce the work-affected layer of the machined surface by carrying out the grinding at the speed over static pr o pagation speed of plastic wave of ductile materials and also aims to clarify suc h super high-speed machining mechanism.This paper reports on the result obtain ed through the molecular dynamics simulations and experiments on the super-spee d grinding below and beyond static propagation speed of aluminum.From the simul ation results,it is verified that the plastic deformation is reduced when the m a chining speed exceeds the material static propagation speed of plastic wave and its mechanism is completely different from that of the ordinary grinding process .Experimental results also show the improvement of the surface integrity when t he machining speed exceeds the material static propagation speed of plastic wave .
基金financially supported by the Royal Golden Jubilee Ph.D. program from the Thailand Research Fund (TRF) on contract No. PHD/0061/2557
文摘The main objective of this research is to study the effect of rib arrangement on the distributions of the local heat transfer coefficient in a stationary channel. In this study, the ribs with square cross section were used to place on two side walls for study. The rib height-to-hydraulic diameter ratio(e/Dh) and the rib pitchto-height(p/e) ratio were fixed at 0.133 and 10, respectively. Three different types of rib arrangement for inclined ribs, V-shaped ribs and inverted V-shaped ribs were investigated. The rib angle of attack(α)was varied from 30?to 90?for inclined ribs and 45?and 60?for both V-shaped and inverted V-shaped ribs, and compared at constant Reynolds number Re =30000. Thermal Liquid Crystal sheet was applied for evaluating the heat transfer distributions. The results showed that the average Nusselt number on surface with rib inclined angle at 60?, 45?, and 60?V-shaped ribs was improved up to about 20%, 25% and 30%higher than case of angle 90?and the rib inclined angle at 60?V-shaped ribs provided the highest Nusselt number covering largest area when compared to the other cases.
基金supported by the National Natural Science Foundation of China (60904002)
文摘An optimal replacement model for gamma deteriorating systems is studied.This methodology uses a gamma distribution to model the material degradation,and the impact of imperfect maintenance actions on the system reliability is investigated.The state of a degrading system immediately after the imperfect maintenance action is assumed as a random variable and the maintenance time follows a geometric process.A maintenance policy(N) is applied by which the system will be repaired whenever it experiences Nth preventive maintenance(PM),and an optimal policy(N) could be determined numerically or analytically for minimizing the long-run average cost per unit time.Finally,a numerical example is presented to demonstrate the use of this policy.
文摘In the optimal control problem of nonlinear dynamical system,the Hamiltonian formulation is useful and powerful to solve an optimal control force.However,the resulting Euler-Lagrange equations are not easy to solve,when the performance index is complicated,because one may encounter a two-point boundary value problem of nonlinear differential algebraic equations.To be a numerical method,it is hard to exactly preserve all the specified conditions,which might deteriorate the accuracy of numerical solution.With this in mind,we develop a novel algorithm to find the solution of the optimal control problem of nonlinear Duffing oscillator,which can exactly satisfy all the required conditions for the minimality of the performance index.A new idea of shape functions method(SFM)is introduced,from which we can transform the optimal control problems to the initial value problems for the new variables,whose initial values are given arbitrarily,and meanwhile the terminal values are determined iteratively.Numerical examples confirm the high-performance of the iterative algorithms based on the SFM,which are convergence fast,and also provide very accurate solutions.The new algorithm is robust,even large noise is imposed on the input data.
基金Project(30917011339)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(BK20170820)supported by the Natural Science Foundation of Jiangsu Province,China+2 种基金Projects(61472267,71471091,71271119)supported by the National Natural Science Foundation of ChinaProject(17KJD110008)supported by the Natural Science Fund for Colleges and Universities in Jiangsu Province,ChinaProject(BE2017663)supported by the Key Research & Developement Plan of Jiangsu Province,China
文摘Possessing the unique and highly valuable properties, graphene sheets(GSs) have attracted increasing attention including that from the building engineer due to the fact that Graphene can be utilized to reinforce concrete and other building materials. In this work, the nonlocal elastic theory and classical plate theory(CLPT) are used to derive the governing equations. The element-free framework for analyzing the buckling behaviors of double layer circular graphene sheets(DLCGSs) relying on an elastic medium is proposed. Pasternak-type model is adopted to describe the elastic medium. Accordingly, the influences of boundary conditions, size of GSs and nonlocal parameters on the buckling behavior of DLCGSs are investigated. The results show that the OP buckling modes are only sensible to the van der Waals forces.
基金Supported by National Key Based Research Project of China under Grant No.2004CB318000National Natural Science Foundation of China under Grant No.10871170
文摘Numerical simulation of antennae is a topic in computational electromagnetism,which is concerned withthe numerical study of Maxwell equations.By discrete exterior calculus and the lattice gauge theory with coefficient R,we obtain the Bianchi identity on prism lattice.By defining an inner product of discrete differential forms,we derivethe source equation and continuity equation.Those equations compose the discrete Maxwell equations in vacuum caseon discrete manifold,which are implemented on Java development platform to simulate the Gaussian pulse radiation onantennaes.
文摘In this paper,a decentralized proportional-derivative(PD)controller design for non-uniform motion of a Hamiltonian hybrid system is considered.A Hamiltonian hybrid system with the capability of producing a non-uniform motion is developed. The structural properties of the system are investigated by means of the theory of Harniltonian systems.A relationship between the parameters of the system and the parameters of the proposed decentralized PD controller is shown to ensure local stability and tracking performance.Simulation results are included to show the obtained non-uniform motion.
基金the Tertiary Education Trust Fund(TETFUND)through the Institutional Based Research(IBR)(Ladoke Akintola University of Technology,Ogbomoso,Nigeria)(2016).
文摘Economic wood processing employs the use of industrial machines for cutting,shaping,milling,and sawing timber,thereby leading to the generation of high levels of noise.Published data from empirical studies have categorized noise as an environmental hazard of global significance.Furthermore,noise exposure limits for different industries and all the industrial machines available has not been formally established as it presently exists in developed nations around the world.Therefore,this study assessed the daily exposure of sawmills workers to noise in Southwestern Nigeria.Reconnaissance surveys were first carried out in Osun,Oyo,Ondo,Ekiti,Lagos,and Ogun States to select sawmills that were fully operational and fit for the study.Two fully functional sawmills in two cities of each State were eventually selected for data collection,making a total of 24 sawmills,while the Circular Machines(CM),Planer Machines(PM),and Band-saw Machines(BM)were the machines in each sawmill considered.Two machines each of CM,PM,and BM were considered in each sawmill,making a total of forty-eight(48)machines each of CM,PM,and BM.Sound data were collected between 7 am and 7 pm each day for six days(between Monday and Saturday)using Extech 407732 sound level meter and all stabilized measurements were taken three times at different intervals.The data collected were in three different periods:Machine No-work Period(NPm),Machine Idle Period(IPm),and Machine Working Period(WPm).A two–way Analysis of Variance(ANOVA)was carried out at P<0.05 to determine whether there is a significant difference in the sound level average before and after the break,for both the idle and working periods of the three machines considered.This was also done to determine whether there is a signifi-cant difference between the sound level average of the results collected during idle and working periods of the three machines.Noise Pollution Levels(Lnp)ranged from 83.20 dB(PM)to 107.65(BM)and 93.42(CM and PM)–116.00(BM)respectively,while IPm also gave the least noise pollution level of 95.79 dB and WPm gave the highest level of 102.88 dB.The results revealed that all the machines’Lnp values in the working period are more than the 90 dB acceptable limit the recommendation value of 90 dB while 89.6%of CMs,75%of PMs,and 89.6%of BM had their Lnp above 90 dB in the idle period respectively.The minimum and the maximum noise dose levels for IPm,WPm and overall are 0.09(BM)and 2.37(CM),0.50(CM),and 4.77(PM)and 0.69(BM)and 6.64(PM)respectively.The study found out that the fundamental contributing factors to the high noise levels in sawmills are poor machine maintenance,use of old and obsolete machines,poor housekeeping strategy,limited space,workers’negligence,lack of PPE,and lack of occupational safety training.The study recommends that proper workplace practices such as use of personal protective equipment,new and modern machines,training,and occupational safety programmes be implemented in the considered sawmills.
基金This research was supported by a grant from R&D Program of the Korea Railroad Research Institute,Republic of Korea.
文摘This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility systems are also increasing,but the railroad electrical facility system in Korea is rapidly aging.To solve this problem,various methodologies are applied to ensure operational reliability and stability for railroad electrical facility systems,but there is a lack of detailed evaluation criteria for railroad electrical facility system maintenance.Also,maintenance items must be selected in a scientific and systematic method.Therefore,railroad electrical facility systems are selected for study.Design StructureMatrix(DSM)is utilized to establish considerations tailored to the maintenance characteristics,and the Fuzzy-TOPSIS methodology is utilized for determining the maintenance detail evaluation item baseline weights,a multi-criteria decision-making problem.Studies show that degradation,insulation items have the highest weight of 14.63%,and capacity items have the lowest weight of 5.34%.The results of this may be contributed to the underlying research in carrying out maintenance activities to ensure the reliability and safety of railroad electrical facility systems.
文摘Effect of viscosity on flow patterns of pumping-up of liquid generated by a cone rotating at the liquid surface has been experimentally studied with various concentrations of glycerol aqueous solution. We have previously found that the higher viscous non-Newtonian fluid was lifted-up along the conical surface with a radial filament-wise pattern, which is quite different from the monotonic thin film-wise pattern observed for the lower viscous fluid such as water. In order to elucidate the pumping-up mechanism, a transition diagram indicating the critical rotation rate is obtained as a function of viscosity?of Newtonian fluid in this study, varying from the lower value of water (μ?=?0.890 mPa·s) to the higher one of glycerin (μ?= 910?mPa·s). It is found that there are three categories depending on the viscosity classified as?1) film-wise pumping-up region for the viscosity?μ?≤?134?mPa·s,?2) filament-wise pumping-up one for the viscosity?μ?≥?520?mPa·s, and?3) no pumping-up phenomenon occurs?for 134??μ??mPa·s.
