Crackles are an important kind of abnormal and discontinuous lung sounds,which have been found to be correlated to types of pulmonary diseases.The purpose of this work is to show a new perspective to solve the problem...Crackles are an important kind of abnormal and discontinuous lung sounds,which have been found to be correlated to types of pulmonary diseases.The purpose of this work is to show a new perspective to solve the problem of crackle detection,based on an emerging theory of fractional Hilbert transform.By applying fractional Hilbert transform to lung sound signals,a two-dimension texture image can be generated.The texture features corresponding to crackles are quite easy to be extracted.Experiments illustrate the effectiveness of our method.展开更多
High speed steel （HSS） rolls can replace traditional rolls such as alloyed cast iron rolls and powder metallurgical （PM） hard alloy rolls. The main reasons for the replacement are that the wear resistance of low-c...High speed steel （HSS） rolls can replace traditional rolls such as alloyed cast iron rolls and powder metallurgical （PM） hard alloy rolls. The main reasons for the replacement are that the wear resistance of low-cost alloyed cast iron rolls is poor and the cost of high-quality PM hard alloy rolls is very high. By means of centrifugal casting, HSS rolls having excellent wear resistance have been manufactured. The hardness of the HSS roll is 6.5～67 HRC, the range of variation is smaller than 2 HRC and its impact toughness is 15 J/cm<sup>2</sup>. The wear rate of HSS rolls used in the pre-finishing stands of high-speed hot wire-rod rolling mill reaches 2.5×10<sup>-4</sup>mm per ton steel. Furthermore, the manufacturing cost of HSS rolls is significantly lower than that of PM hard alloy rolls; it is only 30 percent of that of PM hard alloy rolls.展开更多
The velocity–versus-time rundown curves from two experimental Ti-6Al-4V inertia friction welds were analysed and differentiated several times, to produce rotational acceleration, jerk, jounce (or snap), crackle and p...The velocity–versus-time rundown curves from two experimental Ti-6Al-4V inertia friction welds were analysed and differentiated several times, to produce rotational acceleration, jerk, jounce (or snap), crackle and pop versus-times curves for each weld. Titanium alloys and their mechanical properties are known to be highly sensitive to strain rate as the material is deformed, though nothing has ever been considered in terms of the higher-order time-derivatives of position. These curves have been studied and analysed further, for a more complete understanding of the derivative trends. Rotational acceleration and jerk traces both display behavior patterns across the two welds as the part rotates under action from the flywheel. The rotational snap also displays a pattern in this derivative during the final approximately 0.5 s of welding, as the energy dissipates. Evidence of a distinct oscillatory pattern in the rotational crackle and pop terms was noted for one weld when differentiating over a larger time-base, though could not be replicated in the 2<sup><span style="font-family:Verdana;">nd</span></sup><span style="font-family:Verdana;"> weld. The </span><span style="font-family:Verdana;">higher derivative curves allow distinction of different process regimes, indi</span><span style="font-family:Verdana;">cat</span><span style="font-family:Verdana;">ing that inertial energy mostly influences the time-base of dynamically</span><span style="font-family:Verdana;"> steady-</span><span style="font-family:Verdana;">state phase. Qualitative differences between initial energies are evident in</span><span style="font-family:Verdana;"> higher derivatives.</span>展开更多
文摘Crackles are an important kind of abnormal and discontinuous lung sounds,which have been found to be correlated to types of pulmonary diseases.The purpose of this work is to show a new perspective to solve the problem of crackle detection,based on an emerging theory of fractional Hilbert transform.By applying fractional Hilbert transform to lung sound signals,a two-dimension texture image can be generated.The texture features corresponding to crackles are quite easy to be extracted.Experiments illustrate the effectiveness of our method.
文摘High speed steel （HSS） rolls can replace traditional rolls such as alloyed cast iron rolls and powder metallurgical （PM） hard alloy rolls. The main reasons for the replacement are that the wear resistance of low-cost alloyed cast iron rolls is poor and the cost of high-quality PM hard alloy rolls is very high. By means of centrifugal casting, HSS rolls having excellent wear resistance have been manufactured. The hardness of the HSS roll is 6.5～67 HRC, the range of variation is smaller than 2 HRC and its impact toughness is 15 J/cm<sup>2</sup>. The wear rate of HSS rolls used in the pre-finishing stands of high-speed hot wire-rod rolling mill reaches 2.5×10<sup>-4</sup>mm per ton steel. Furthermore, the manufacturing cost of HSS rolls is significantly lower than that of PM hard alloy rolls; it is only 30 percent of that of PM hard alloy rolls.
文摘The velocity–versus-time rundown curves from two experimental Ti-6Al-4V inertia friction welds were analysed and differentiated several times, to produce rotational acceleration, jerk, jounce (or snap), crackle and pop versus-times curves for each weld. Titanium alloys and their mechanical properties are known to be highly sensitive to strain rate as the material is deformed, though nothing has ever been considered in terms of the higher-order time-derivatives of position. These curves have been studied and analysed further, for a more complete understanding of the derivative trends. Rotational acceleration and jerk traces both display behavior patterns across the two welds as the part rotates under action from the flywheel. The rotational snap also displays a pattern in this derivative during the final approximately 0.5 s of welding, as the energy dissipates. Evidence of a distinct oscillatory pattern in the rotational crackle and pop terms was noted for one weld when differentiating over a larger time-base, though could not be replicated in the 2<sup><span style="font-family:Verdana;">nd</span></sup><span style="font-family:Verdana;"> weld. The </span><span style="font-family:Verdana;">higher derivative curves allow distinction of different process regimes, indi</span><span style="font-family:Verdana;">cat</span><span style="font-family:Verdana;">ing that inertial energy mostly influences the time-base of dynamically</span><span style="font-family:Verdana;"> steady-</span><span style="font-family:Verdana;">state phase. Qualitative differences between initial energies are evident in</span><span style="font-family:Verdana;"> higher derivatives.</span>
基金supported by the Shenzhen Basic Research Program(JCYJ20180306173007696)the Natural Science Foundation of Fujian Province(2017J01104)+4 种基金the Fundamental Research Funds for the Central Universities of China(20720160127,20720180013)Doctoral Fund of the Ministry of Education(20130121110018)NUS AcRF Tier 1(R-144-000-367-112)the“111”Project(B16029)the 1000 Talents Program Funding from the Xiamen University.
