期刊文献+
共找到37篇文章
< 1 2 >
每页显示 20 50 100
植物投放密度对富营养化湖水修复效率的影响 被引量:7
1
作者 王海鸥 钟广蓉 +3 位作者 刘虎 王垚 张纯 闫海 《安徽农业科学》 CAS 北大核心 2009年第23期11124-11126,共3页
[目的]研究几种植物混种对富营养化水体的净化效果。[方法]以小瓜子、缎带椒、中柳、皇冠和西瓜草5种植物为试材,以北京市延庆县妫水湖8月份富营养化程度最高的湖水为植物生长基质,设高、中、低3个投放密度试验组,研究植物投放密度对富... [目的]研究几种植物混种对富营养化水体的净化效果。[方法]以小瓜子、缎带椒、中柳、皇冠和西瓜草5种植物为试材,以北京市延庆县妫水湖8月份富营养化程度最高的湖水为植物生长基质,设高、中、低3个投放密度试验组,研究植物投放密度对富营养化湖水的修复效率影响;通过测定水样中总磷酸盐(TP)、总氮(TN)、氨氮和硝态氮的浓度变化,确定植物修复的最佳效率。[结果]所有植物试验组对富营养化水中氨氮的净化效果均比较显著。3个试验组中,以投放低密度试验组对氨氮吸收的处理效果比较好,对硝氮吸收的处理效果较为明显;投放中密度试验组对于总氮和磷酸盐吸收的处理效果较为明显。[结论]适当控制植物的投放密度有利于去除富营养化物质。 展开更多
关键词 水生植物 富营养化 投放密度 修复效率
下载PDF
基于脑电图的帕金森轻度认知障碍功能网络特征分析 被引量:1
2
作者 李昕 张晴 +2 位作者 张莹 谢平 尹立勇 《计量学报》 CSCD 北大核心 2024年第1期135-144,共10页
帕金森氏轻度认知障碍(PDMCI)是帕金森氏症患者痴呆的先兆,这对使用神经评分量表和医生经验等传统方法进行准确诊断提出了挑战。利用26名PDMCI患者和23名正常人的脑电信号,基于定向传递函数构建了Delta、Theta、Alpha、Beta和Gamma频段... 帕金森氏轻度认知障碍(PDMCI)是帕金森氏症患者痴呆的先兆,这对使用神经评分量表和医生经验等传统方法进行准确诊断提出了挑战。利用26名PDMCI患者和23名正常人的脑电信号,基于定向传递函数构建了Delta、Theta、Alpha、Beta和Gamma频段的脑功能网络。引入了一种新颖的图论特征——效率密度来捕获网络密度和传输效率。研究结果揭示了独特的连接模式,Delta和Theta波段的连接更紧密,而Alpha、Beta和Gamma波段的连接更稀疏。帕金森病(PD)患者与对照组之间的Theta、Alpha、Beta和Gamma频带存在显著差异(p<0.05)。因此,脑功能网络可以有效反映PD脑功能异常状态,效率密度特征可以反映PD脑功能异常活动的特征量。 展开更多
关键词 智能信息处理 帕金森轻度认知障碍 脑电 脑功能网络 特征提取 效率密度
下载PDF
宽输出适应的兆赫兹高效率高功率密度DC-DC变换器研究
3
作者 严军 李光灿 吴新科 《现代雷达》 CSCD 北大核心 2022年第7期98-101,共4页
对于雷达电源系统中高压转低压的DC/DC应用场景,目前基于高压硅器件的方案受制于器件寄生参数的影响,开关频率一般在数百kHz以内,难以进一步提升效率和功率密度。文中利用NFoM较低的低压硅器件,提出了利用低压电路单元链式串并联的方法... 对于雷达电源系统中高压转低压的DC/DC应用场景,目前基于高压硅器件的方案受制于器件寄生参数的影响,开关频率一般在数百kHz以内,难以进一步提升效率和功率密度。文中利用NFoM较低的低压硅器件,提出了利用低压电路单元链式串并联的方法以实现更高电压的功率变换,该方法能够适应雷达电源系统多种输入输出电压变换需求,并且在MHz开关频率下能够实现较高的效率和功率密度。最后以380 Vdc/48 Vdc的应用场合为例设计并实现了实验样机,实现了98.0%的峰值效率,在1 800 W的满载功率下,样机的功率密度超过800 W/in^(3)。 展开更多
关键词 雷达电源系统 DC/DC变换模块 串并联 效率高功率密度
原文传递
基于氮化镓的高频LLC变换器研究
4
作者 荣振帅 迟迎超 +2 位作者 孙战 王懿杰 徐殿国 《电气传动》 2023年第2期3-9,共7页
5G时代的到来对电源系统提出了更高的要求,即要求变换器具有高效率、高功率密度以及快速动态响应。针对该问题,使用第三代宽禁带半导体器件氮化镓(GaN)晶体管,优化变压器结构,采用新型分数匝结构,通过DSP数字控制方法设计一款400 V转12 ... 5G时代的到来对电源系统提出了更高的要求,即要求变换器具有高效率、高功率密度以及快速动态响应。针对该问题,使用第三代宽禁带半导体器件氮化镓(GaN)晶体管,优化变压器结构,采用新型分数匝结构,通过DSP数字控制方法设计一款400 V转12 V、输出功率为500 W的高效率、高功率密度LLC谐振变换器。通过理论分析高频状态下实际LLC电路参数影响,确定系统优化方向,并结合有限元仿真软件改进分数匝变压器结构,最后搭建实物平台验证理论的可行性。 展开更多
关键词 LLC谐振变换器 氮化镓 分数匝变压器 效率与高功率密度
下载PDF
闪电定位资料与目测雷暴日的对比分析 被引量:32
5
作者 钟颖颖 冯民学 +2 位作者 周曾奎 王锡中 张艳华 《气象科学》 CSCD 北大核心 2010年第6期851-855,共5页
对比分析了2006—2008年4—8月江苏省气象局闪电定位系统数据和6个地面观测站雷暴数据,通过计算测站有雷暴记录同时闪电探测网有闪电记录的比例和有地闪记录同时有雷暴记录的比例,得出两种观测数据的一致性较好;同时以目测资料为准,借... 对比分析了2006—2008年4—8月江苏省气象局闪电定位系统数据和6个地面观测站雷暴数据,通过计算测站有雷暴记录同时闪电探测网有闪电记录的比例和有地闪记录同时有雷暴记录的比例,得出两种观测数据的一致性较好;同时以目测资料为准,借助雷达数据判别分析了闪电定位系统的漏测率和误测率,表明省气象局闪电定位系统探测数据有效。江苏省水体分布广泛,南北地形差异较大,闪电分布也不同,本文针对不同地形地貌利用两种观测数据计算了适用于各个地区的地闪密度公式。 展开更多
关键词 闪电定位 雷暴日 地闪密度探测效率
下载PDF
Numerical Study of Optimization of Layer Thickness in Bilayer Organic Light-Emitting Diodes 被引量:3
6
作者 彭应全 张磊 张旭 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2003年第5期454-460,共7页
A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and c... A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and carrier mobility of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure anode/HTL/EML/cathode are numerically investigated.It is found that,for given values of the total thickness of organic layers,reduced depth of trap,total density of trap,and carrier mobility of HTL as well as EML,there exists an optimal thickness ratio of HTL to EML,by which a maximal quantum efficiency can be achieved.Through optimization of the thickness ratio,an enhancement of current density and quantum efficiency of as much as two orders of magnitude can be obtained.The dependences of the optimal thickness ratio to the characteristic trap energy,total density of trap and carrier mobility are numerically analyzed. 展开更多
关键词 organic light-emitting diodes BILAYER OPTIMIZATION
下载PDF
Suitable Date of Seeding, Planting Density and Water Use Efficiency for Propagation of Stock Seed Potato in Mountainous Region of Southwest Sichuan 被引量:2
7
作者 沈学善 罗李飞 +1 位作者 李春荣 黄钢 《Agricultural Science & Technology》 CAS 2012年第9期1904-1907,共4页
[Objective] The experiment was conducted to study suitable date of seed- ing and density of spring potato at the stock breeding base in Ebian County at an elevation of 1 200 to 1 500 m. [Methods] Virus-free Potato "C... [Objective] The experiment was conducted to study suitable date of seed- ing and density of spring potato at the stock breeding base in Ebian County at an elevation of 1 200 to 1 500 m. [Methods] Virus-free Potato "Chuanyu 13" was used as material to study the effects of date of seeding and density on growing period, germination rate, yield and water use efficiency of spring potato in the field. [Result] With the postponement of date of seeding, the days from sowing to germination shortened, while the germination rate, the number of tubers per plant, the number of middle and small tubers in a group, yield and water use efficiency all increased. Planting density had no effects on the days from sowing to germination and the ger- mination rate, while the number of tubers per ptant, the number of middle and small tubers in a group, yield and water use efficiency increased significantly along with the increasing planting density. [Conclusion] At an elevation of 1 200 m to 1 250 m in Ebian County, the suitable date of seeding for potato was from February 9 to March 1, and the suitable planting density was 12×10^4 plants per hm^2, however, in the optimum planting density has not been found so that it needs further research, 展开更多
关键词 Date ofseedingi Planting density Stock seed YIELD Water use efficiency
下载PDF
串联谐振间接矩阵型电力电子变压器高频电流特性分析及开关频率设计 被引量:14
8
作者 胡钰杰 李子欣 +2 位作者 罗龙 赵聪 李耀华 《电工技术学报》 EI CSCD 北大核心 2022年第6期1442-1454,共13页
串联谐振间接矩阵型电力电子变压器(PET)通过高频开关并减小直流电容容值可实现高功率密度。然而,小直流电容会改变谐振回路等效电容,并影响高频谐振电流特性,进而影响零电流软开关(ZCS)的实现。该文建立小直流电容下串联谐振间接矩阵型... 串联谐振间接矩阵型电力电子变压器(PET)通过高频开关并减小直流电容容值可实现高功率密度。然而,小直流电容会改变谐振回路等效电容,并影响高频谐振电流特性,进而影响零电流软开关(ZCS)的实现。该文建立小直流电容下串联谐振间接矩阵型PET等效电路,推导高频电流时域解析表达式,并对ZCS条件下的开关频率进行设计,揭示直流电容和死区时间对开关频率的影响规律。仿真和实验结果验证了该文理论分析的正确性。 展开更多
关键词 AC-AC电力电子变压器 串联谐振 间接矩阵变换器 高频电流特性 零电流软开关(ZCS) 高功率密度和高效率
下载PDF
Effect of Stem Density on Leaf Nutrient Dynamics and Nutrient Use Efficiency of Dwarf Bamboo 被引量:4
9
作者 WU Fu-Zhong YANG Wan-Qin +2 位作者 WANG Kai-Yun WU Ning LU Ye-Jiang 《Pedosphere》 SCIE CAS CSCD 2009年第4期496-504,共9页
The monthly dynamics of nitrogen (N) and phosphorus (P) concentrations and stocks in leaves, resorption efficiency, and resorption proficiency as well as leaf-level use efficiency, nutrient productivity, and mean ... The monthly dynamics of nitrogen (N) and phosphorus (P) concentrations and stocks in leaves, resorption efficiency, and resorption proficiency as well as leaf-level use efficiency, nutrient productivity, and mean residence time were studied to understand the effect of stem density of dwarf bamboo (Fargesia denudata Yi) on leaf-level N and P use efficiency in three dwarf bamboo stands with different stem densities under bamboo-fir (Picea puvpurea Mast.) forest over one growing period in the Wanglang National Nature Reserve, Sichuan, China. Dwarf bamboo density had little effect on the dynamics pattern of both N and P concentrations, stocks, resorption efficiency, and resorption proficiency, but strongly affected their absolute values and leaf-level use efficiency. Higher density stands stored more nutrients but had lower concentrations. There was a clear difference in the resorption of limiting nutrient (N) and non-limiting nutrient (P) among the stands. Phosphorus resorption efficiency, N resorption proficiency, and P resorption proficiency increased with increase of stem density, but no significant variation of N resorption efficiency was found among the stands. Moreover, the higher density stands used both N and P more efficiently with higher N productivity and higher P mean residence time, respectively. Higher P productivity was found in the lower density stands, but there was no clear variation in the N mean residence time among stands. These suggested that the higher density stands may have more efficient strategies for utilizing nutrients, especially those which are limiting . 展开更多
关键词 mean residence time nutrient productivity nutrient resorption
下载PDF
Stark Effect Dependence on Hydrogenic Impurities in GaAs Parabolic Quantum-Well Wires 被引量:1
10
作者 WANG Sheng WEI Guo-Zhu HAN Yu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第11期953-959,共7页
The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolic quantum-well wires (Q WWs) subjected to external electric and magnetic fields are investigated using the finite-d... The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolic quantum-well wires (Q WWs) subjected to external electric and magnetic fields are investigated using the finite-difference method within the quasi-one-dimensional effective potential model. We define an effective radius Pen of a cylindrical QWW, which can describe the strength of the lateral confinement. For the ground state, the position of the largest probability density of electron in x-y plane is located at a point, while for the lowest excited state, is located on a circularity whose radius is Pen. The point and circularity are pushed along the left haft of the center axis of the quantum-well wire by the electric field dire ted along the right half. When an impurity is located at the point or within the circularity, the ground-state or lowest excited-state binding energies are the largest; when the impurity is apart from the point or circularity, the ground-state or lowest excited-state binding energies start to decrease. 展开更多
关键词 hydrogenic impurity quantum-well wire magnetic field binding energy
下载PDF
Absorption of NO_x into Nitric Acid Solution in Rotating Packed Bed 被引量:22
11
作者 李裕 刘有智 +2 位作者 张路遥 苏强 金国良 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2010年第2期244-248,共5页
Absorption of NOx into nitric acid solutions was studied in the presence of ozone by using a rotating packed bed(RPB) contactor.The influences of operating parameters,such as high gravity number,amount of ozone,gas ve... Absorption of NOx into nitric acid solutions was studied in the presence of ozone by using a rotating packed bed(RPB) contactor.The influences of operating parameters,such as high gravity number,amount of ozone,gas velocity,liquid spray density and inlet concentration of NOx,on the removal efficiency of NOx were investigated,among which the high gravity number and ozone amount are more important.Ozone was introduced to oxidize HNO2 to HNO3 to prevent the decomposition of HNO2 in the liquid phase.The high gravity number presents the effective external force for enhancing the mass transfer of ozone from gas phase to liquid phase.Under the experimental condition,the removal efficiency of NOx is higher than 90%and the concentration of nitric acid product exceeds 45%. 展开更多
关键词 nitrogen oxides rotating packed bed ozone oxidation ABSORPTION
下载PDF
Characteristics of fluidization and dry-beneficiation of a wide-size-range medium-solids fluidized bed 被引量:2
12
作者 Tang Ligang 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第3期467-471,共5页
Wide-size-range medium-solids are used in a modularized coal beneficiation demonstration system with a gas-solid fluidized bed. The characteristics of fluidization and dry-beneficiation of the medium solids were studi... Wide-size-range medium-solids are used in a modularized coal beneficiation demonstration system with a gas-solid fluidized bed. The characteristics of fluidization and dry-beneficiation of the medium solids were studied. The numerical simulation results show that 0.15–0.06 mm fine magnetite powder can decrease the disturbances caused by the bubbles. This is beneficial to the uniformity of the gas-solid interactions and thus to the uniformity and stability of the bed density and height. The experimental results show that, with an increase in the fine coal content in medium solids, both the fluidization quality and the beneficiation performance of the bed decreased gradually. When the fine coal content was no more than 13%, a relatively high superficial gas velocity increased the beneficiation efficiency. When the content was more than 13%, part of the fine coal was separated, leading to product layers. The separation efficiency was therefore gradually decreased. The models for predicting the bed density standard deviation and the probable error, E, value were both proposed. The E value can reach to 0.04–0.07 g/cm^3 under the optimized experimental parameters. This work provides a foundation for the adjustment of the bed density and the separation performance of the modularized 40–60 ton per hour dry coalbeneficiation industrial system. 展开更多
关键词 Medium solids Wide size range Gas-solid fluidized bed Fluidization Dry beneficiation of coal
下载PDF
铁路信号电源系统中直流电源模块优化设计 被引量:2
13
作者 吴庆丰 《铁路通信信号工程技术》 2022年第11期115-120,共6页
为提高铁路信号电源系统设备系统效率和功率密度,对电源系统中使用较多的直流开关电源模块进行分析,针对典型拓扑电路提出优化方案。在电路中应用宽禁带半导体器件,前级采用无桥功率因数校正(PowerFactorCorrection,PFC)电路实现功率因... 为提高铁路信号电源系统设备系统效率和功率密度,对电源系统中使用较多的直流开关电源模块进行分析,针对典型拓扑电路提出优化方案。在电路中应用宽禁带半导体器件,前级采用无桥功率因数校正(PowerFactorCorrection,PFC)电路实现功率因数校正功能,后级采用交错并联LLC谐振软开关拓扑电路实现不同直流电压的隔离变换。优化方案能够有效提高直流开关电源模块的效率和功率密度,提高电源模块的可靠性。 展开更多
关键词 直流开关电源模块 功率因数校正 交错并联 LLC谐振变换器 效率和功率密度
下载PDF
Cross-Layer Framework for Fine-Grained Channel Access in Next Generation High-Density Wi Fi Networks 被引量:2
14
作者 ZHAO Haitao ZHANG Shaojie Emiliano Garcia-Palacios 《China Communications》 SCIE CSCD 2016年第2期55-67,共13页
Densely deployed Wi Fi networks will play a crucial role in providing the capacity for next generation mobile internet. However, due to increasing interference, overlapped channels in Wi Fi networks and throughput eff... Densely deployed Wi Fi networks will play a crucial role in providing the capacity for next generation mobile internet. However, due to increasing interference, overlapped channels in Wi Fi networks and throughput efficiency degradation, densely deployed Wi Fi networks is not a guarantee to obtain higher throughput. An emergent challenge is how to effi ciently utilize scarce spectrum resources, by matching physical layer resources to traffi c demand. In this aspect, access control allocation strategies play a pivotal role but remain too coarse-grained. As a solution, this research proposes a flexible framework for fine-grained channel width adaptation and multi-channel access in Wi Fi networks. This approach, named SFCA(Subcarrier Fine-grained Channel Access), adopts DOFDM(Discontinuous Orthogonal Frequency Division Multiplexing) at the PHY layer. It allocates the frequency resource with a subcarrier granularity, which facilitates the channel width adaptation for multi-channel access and thus brings more fl exibility and higher frequency efficiency. The MAC layer uses a frequencytime domain backoff scheme, which combines the popular time-domain BEB scheme with a frequency-domain backoff to decrease access collision, resulting in higher access probability for the contending nodes. SFCA is compared with FICA(an established access scheme)showing significant outperformance. Finally we present results for next generation 802.11 ac Wi Fi networks. 展开更多
关键词 channel width adaptation channel access high-density WiFi
下载PDF
Method of 3D Solar Energy Conversion
15
作者 Valeri I. Kotelnikov Elena A. Ryazanova 《Journal of Mechanics Engineering and Automation》 2016年第4期212-216,共5页
The problem of collecting solar energy and increasing its efficiency was studied in this paper. It was discovered that a 3DPV (three-dimensional photovoltaic) structures can generate greater amounts of measured ener... The problem of collecting solar energy and increasing its efficiency was studied in this paper. It was discovered that a 3DPV (three-dimensional photovoltaic) structures can generate greater amounts of measured energy densities than stationary flat PV panels (rate: 2 to 20). It has been found that the same structures work better not only because they are made in 3D but because PV panels do not have linear dependency on geometry. It seems that the conversion efficiency depends on the process of absorption of the solar energy, too, or in other words on the E. Yablonovich limit. The findings suggest that the quantity of material of solar panels may be reduced to generate the same amount of electricity. 展开更多
关键词 Solar energy EFFICIENCY photovoltaic technology electricity generation energy transmission.
下载PDF
Electrochemical Treatment of Distillery Spent Wash Using Aluminum and Iron Electrodes
16
作者 V.Khandegar Anil.K.Saroha 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第3期439-443,共5页
Electrochemical treatment of distillery .spentwash was carried out using different combinations of aluminum and iron electrodes in batch mode of operation. The spent wash was characterized for various parameters as pe... Electrochemical treatment of distillery .spentwash was carried out using different combinations of aluminum and iron electrodes in batch mode of operation. The spent wash was characterized for various parameters as per standard method of analysis and the treatment results were analyzed in terms of chemical oxygen demand (COD) removal efficiency o.f thespent.wash. The experiments were performed to s.tudy the effect of operating parameterssuch as current density, pH of the spent wash, agitation speed, electrolysis time and the distance between the elec- trodes on the COD removal efficiency of the spent wash. It was observed that aluminum electrodes were more suitable for treatment of distillery spent wash as compared to iron electrodes. The maximum COD removal effi- ciency of 81.3% was obtained with A1-A1 electrodes at the current density of 0.187 A.cm-2 and pH 3 for an elec-trolysis time of 2 h. 展开更多
关键词 ELECTROCOAGULATION distillery spent wash current density aluminum iron
下载PDF
Sensibility Analysis of the Brazilian Standards for Energy Efficiency Regarding the Variation of Internal Load Density in Office Buildings in Brazilian Bioclimatic Zones 1 and 7
17
作者 Mariane Pinto Brandalise Eduardo Grala da Cunha Larissa Cristina de Oliveira 《Journal of Civil Engineering and Architecture》 2016年第1期22-36,共15页
The RTQ-C (Technical Requirements of Quality for the Energy Performance Level of Commercial Buildings) publication classified the buildings in five efficiency levels. In RTQ-C, the evaluation can be done with two me... The RTQ-C (Technical Requirements of Quality for the Energy Performance Level of Commercial Buildings) publication classified the buildings in five efficiency levels. In RTQ-C, the evaluation can be done with two methods: a prescriptive method and a simulation one. This paper aims to identify the sensibility of the prescriptive method RTQ-C regarding the variation of equipment internal load density in office buildings in bioclimatic Zones I and 7 of the Brazilian bioclimatic zoning. The research results show that the building with walls and roof configured to meet specific prerequisites for energy efficiency Levels B and C had a lower consumption than buildings that meet the prerequisites to Level A. The study also showed that buildings with high internal load density of equipment, maximum shape factor and high, with walls and roofs with higher thermal transmittance, have lower power consumption than constructions with an envelope with greater thermal resistance. The increase in internal load density causes an increase in the internal heat generated by the large amount of equipment. In buildings with higher thermal insulation (Level A), the internal heat is maintained in the environment, causing overheating and the need for an air conditioning system. 展开更多
关键词 RTQ-C internal load density office buildings energy modeling energy efficiency in buildings.
下载PDF
Future Outlook of Artificial Cavity Application for Reducing Hydrodynamic Resistance of Containerships
18
作者 Valery Borusevich Alexander Poustoshnyl +1 位作者 Andrey Sverchkov Giorgio Trincas 《Journal of Energy and Power Engineering》 2017年第3期150-159,共10页
Absolute commitment to reduce the impact of greenhouse gas emissions while increasing fuel efficiency and power density requires further enhancement of prime mover characteristics and special coatings, but mostly requ... Absolute commitment to reduce the impact of greenhouse gas emissions while increasing fuel efficiency and power density requires further enhancement of prime mover characteristics and special coatings, but mostly requires compliance with EEDI (energy efficiency design index) measures. For the container shipping industry this represents significant increases in fuel costs that can be mitigated above all by reduction of power demand, that is, of ship frictional resistance. In this respect, this paper discusses advantages attainable by application of the ACS (air cavity system) technology on the basis of recent KSRC (Krylov State Research Centre) studies Savings in operating costs yielded by the enhanced propulsion performance for ships fitted with this system are illustrated by a case study of a containership. 展开更多
关键词 Air cavity containership fuel saving energy efficiency green ship.
下载PDF
The Effect of Stocking Density on the Behaviour and Welfare Indexes of Broiler Chickens
19
作者 Jang-Ho Son 《Journal of Agricultural Science and Technology(A)》 2013年第4期307-311,共5页
The effect of three stocking densities, ranging from 30 to 44 kg product per m2 on the performance, behaviour and welfare indexes in broiler chicken was investigated. Scan sampling for comparative behavior in all grou... The effect of three stocking densities, ranging from 30 to 44 kg product per m2 on the performance, behaviour and welfare indexes in broiler chicken was investigated. Scan sampling for comparative behavior in all groups was carried out at 2 min intervals during 2-20 min periods for five days each week. It was found that the most common behaviour in all densities was lying (resting), lying and standing behaviour was tended to increase in H than L group of all experimental period. Pecking behaviour was not constantly changed by stocking density. Locomotion was not only reduced with increasing age but increase stocking density of all experimental period and all groups. Body weight gain and feed efficient were, tend to increase in L than H group of 2 to 3 weeks ages, higher in L than H group (P 〈 0.05) of 4 to 5 weeks ages and all experimental period. Other behaviours (dustbathing, preening, eating or drinking) were not influenced (P 〉 0.05) by stocking density. It seems that gait, foot pad and hock burn score were improved in L than H group of 35 days age (P 〈 0.05). The claw length of 21 days age was not affected by stocking density, but it was significantly different by stocking density of 35 days age (P 〈 0.05). The duration of tonic immobility (TI-reaction) was tended to decreased age of 21 than 35 days, but not effected by stocking density. These data indicate that stocking density can influence broiler behaviour and welfare indexes. 展开更多
关键词 BROILER stocking density PERFORMANCE BEHAVIOUR welfare indexes
下载PDF
Energy Efficiency Building Codes for Egypt
20
作者 G.B. Hanna 《Journal of Energy and Power Engineering》 2011年第12期1134-1141,共8页
This paper summarizes the results of energy simulation analysis to determine the effectiveness of building characteristics in reducing electrical energy consumption in residential buildings (conditioned and unconditi... This paper summarizes the results of energy simulation analysis to determine the effectiveness of building characteristics in reducing electrical energy consumption in residential buildings (conditioned and unconditioned) and commercial buildings (office & hotel) in Egypt. Specifically, the impact on building envelope performance is investigated for different strategies such as window size, glazing type and building construction for two geographical locations in Egypt. This paper also studies the energy savings in residential and nonresidential buildings for different lighting power densities (LPD), energy input ratios (EIR), set point temperatures (SPT) and heating, ventilation, and air conditioning (I-WAC) systems. The study shows certain findings of practical significance, e.g. that a window-to-wall ratio of 0.20 and reasonably shaded windows lower the total annual electricity use for nonresidential buildings by more than 20% in the two Egyptian locations. 展开更多
关键词 Energy codes simulation VDOE WWR LPD EPD SPT EIR.
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部