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Relative energy zero ratio-based approach for identifying pulse-like ground motions 预览
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作者 Liu Ping Li Ning +2 位作者 Ma Hua Xie Lili Zhou Baofeng 《地震工程与工程振动:英文版》 SCIE EI CSCD 2020年第1期1-16,共16页
Pulse-like ground motions are capable of inflicting significant damage to structures. Efficient classification of pulse-like ground motion is of great importance when performing the seismic assessment in near-fault re... Pulse-like ground motions are capable of inflicting significant damage to structures. Efficient classification of pulse-like ground motion is of great importance when performing the seismic assessment in near-fault regions. In this study, a new method for identifying the velocity pulses is proposed, based on different trends of two parameters: the short-time energy and the short-time zero crossing rate of a ground motion record. A new pulse indicator, the relative energy zero ratio(REZR), is defined to qualitatively identify pulse-like features. The threshold for pulse-like ground motions is derived and compared with two other identification methods through statistical analysis. The proposed procedure not only shows good accuracy and efficiency when identifying pulse-like ground motions but also exhibits good performance for classifying records with high-frequency noise and discontinuous pulses. The REZR method does not require a waveform formula to express and fit the potential velocity pulses;it is a purely signal-based classification method. Finally, the proposed procedure is used to evaluate the contribution of pulse-like motions to the total input energy of a seismic record, which dramatically increases the seismic damage potential. 展开更多
关键词 pulse-like ground motion velocity pulse relative energy zero-crossing ratio short-time input energy shorttime zero crossing rate
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双作用子母叶片泵配流副油膜流场的数值分析 预览
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作者 李少年 张磊 +1 位作者 赵茹 胡振铭 《液压与气动》 北大核心 2020年第2期44-49,共6页
在建立双作用子母叶片泵配流副的油膜体模型后,运用CFD软件对其流场区域进行流场仿真,得到该配流副油膜的压力和速度分布。分析结果表明:油膜高压区主要集中在排油阻尼槽和排油区的叶片中间腔分油槽附近。双作用子母叶片泵配流盘配流均... 在建立双作用子母叶片泵配流副的油膜体模型后,运用CFD软件对其流场区域进行流场仿真,得到该配流副油膜的压力和速度分布。分析结果表明:油膜高压区主要集中在排油阻尼槽和排油区的叶片中间腔分油槽附近。双作用子母叶片泵配流盘配流均压槽较多,使得配流副油膜油液的流动较复杂,油液流动速度很快,且由于油膜内部存在射流现象,导致在高压槽附近出现了负压区域。当转速增加时,压力分布的规律并不会随着转速的增加发生太大的改变,但全速度在油膜高压区由于动压作用的影响反而会减小。径向速度主要受压差作用影响,随着转速增加基本没有变化。 展开更多
关键词 子母叶片泵 配流副 油膜 压力 速度
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基于Fluent的线切割机床管道流场分析 预览
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作者 曹劲草 《液压气动与密封》 2020年第1期12-15,共4页
线切割机床在加工工件的过程中,需要不断喷出工作液对工件进行降温、除渣、绝缘。在此过程中,工作液循环系统常常会发生排水不畅的现象。以CTW320TB线切割机床排水管道为主要研究对象,采用UG软件建模,在Fluent软件模拟不同入口流速下管... 线切割机床在加工工件的过程中,需要不断喷出工作液对工件进行降温、除渣、绝缘。在此过程中,工作液循环系统常常会发生排水不畅的现象。以CTW320TB线切割机床排水管道为主要研究对象,采用UG软件建模,在Fluent软件模拟不同入口流速下管道内的压力分布情况以及管道出口处的流速分布情况,并以此来分析线切割机床管道排水不畅的原因。 展开更多
关键词 线切割机床 管道 FLUENT 压力 流速
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Transdermal delivery of 4-aminopyridine accelerates motor functional recovery and improves nerve morphology following sciatic nerve crush injury in mice 预览
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作者 Andrew RClark Chia George Hsu +2 位作者 M A Hassan Talukder Mark Noble John CElfar 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第1期136-144,共9页
Oral 4-aminopyridine(4-AP)is clinically used for symptomatic relief in multiple sclerosis and we recently demonstrated that systemic 4-AP had previously unknown clinically-relevant effects after traumatic peripheral n... Oral 4-aminopyridine(4-AP)is clinically used for symptomatic relief in multiple sclerosis and we recently demonstrated that systemic 4-AP had previously unknown clinically-relevant effects after traumatic peripheral nerve injury including the promotion of re-myelination,improvement of nerve conductivity,and acceleration of functional recovery.We hypothesized that,instead of oral or injection administration,transdermal 4-AP(TD-4-AP)could also improve functional recovery after traumatic peripheral nerve injury.Mice with surgical traumatic peripheral nerve injury received TD-4AP or vehicle alone and were examined for skin permeability,pharmacokinetics,functional,electrophysiological,and nerve morphological properties.4-AP showed linear pharmacokinetics and the maximum plasma 4-AP concentrations were proportional to TD-4-AP dose.While a single dose of TD-4-AP administration demonstrated rapid transient improvement in motor function,chronic TD-4-AP treatment significantly improved motor function and nerve conduction and these effects were associated with fewer degenerating axons and thicker myelin sheaths than those from vehicle controls.These findings provide direct evidence for the potential transdermal applicability of 4-AP and demonstrate that 4-AP delivered through the skin can enhance in-vivo functional recovery and nerve conduction while decreasing axonal degeneration.The animal experiments were approved by the University Committee on Animal Research(UCAR)at the University of Rochester(UCAR-2009-019)on March 31,2017. 展开更多
关键词 4-AMINOPYRIDINE electron MICROSCOPY functional recovery NERVE conduction velocity PERIPHERAL NERVE injury PHARMACOKINETICS TRANSDERMAL administration
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The formation bulk density prediction for intact and fractured siliciclastic rocks
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作者 Babatunde Yusuf Olalere Oloruntobi Stephen Butt 《大地测量与地球动力学:英文版》 2019年第6期446-454,共9页
The formation bulk density is one of the most important rock properties required for reservoir evaluation and geomechanical analysis.In intervals where the formation bulk density logs are not acquired,the industry pra... The formation bulk density is one of the most important rock properties required for reservoir evaluation and geomechanical analysis.In intervals where the formation bulk density logs are not acquired,the industry practice is to estimate the formation bulk density from the compressional-wave velocity using empirical relationships.The major problems with the existing empirical relationships are:(1)they were developed primarily for specific lithologies(in most cases clean formations)and have failed to produce reasonable estimates when applied over a lithological column that consists of several stratigraphic units;(2)they are not applicable to rocks that contain microcracks/fractures.In this paper,a new formation bulk density prediction method that can be applied to a wide range of intact and fractured siliciclastic rocks is being proposed based on experimental data.The model is then validated using wireline log data acquired from an onshore well in the tertiary deltaic system of the Niger Delta basin.In the new model,the formation bulk density is expressed as a function of sonic velocity difference and shale volume factor.In general,an excellent agreement exists between the predicted and measured formation bulk density using the new technique.The statistical analysis shows that the new formation bulk density prediction model outperforms the most widely used empirical relationships with the least-root-mean square errors and least residual values. 展开更多
关键词 BULK density Compressional WAVE VELOCITY SHEAR WAVE VELOCITY LITHOLOGY
Anomalous SmKS induced by postcritical reflection and refraction at the core-mantle boundary
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作者 Liwei Wang Fenglin Niu 《科学通报:英文版》 SCIE EI CSCD 2019年第21期1601-1607,共7页
Earth’s outer core is generally thought to be a well-mixed liquid consisting mostly of iron and a small amount of lighter elements.Recent seismic studies using Sm KS waves show that the top a few hundred kilometers o... Earth’s outer core is generally thought to be a well-mixed liquid consisting mostly of iron and a small amount of lighter elements.Recent seismic studies using Sm KS waves show that the top a few hundred kilometers of the outer core possess a P-wave velocity slightly lower than the PREM model,which cannot be explained by self-compression of a chemically homogeneous outer core.We investigated the Sm KS waveforms of a deep earthquake occurring beneath South America recorded by a large and dense seismic array in China,and measured the differential arrival times of the Sm KS pairs.We found significant waveform distortion of the Sm KS caused by postcritical refraction and reflection at the core-mantle boundary.This waveform distortion can introduce significant bias to the measured differential times,leading to incorrect estimate of P-wave velocity of the outer core.Whether stable stratification is occurring in outer core or not requires further seismic investigations. 展开更多
关键词 SmKS HILBERT transform Postcritical phase SHIFT Outer-core P-WAVE velocity Outer CORE STRATIFICATION Ultra-low-velocity-zone
Effects of vegetation patch density on flow velocity characteristics in an open channel 预览
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作者 Wen-qi Li Dan Wang +1 位作者 Jun-li Jiao Ke-jun Yang 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第5期1052-1059,共8页
The aquatic plants are often found in natural rivers,and they affect the channel flow structure significantly.To study the effects of the vegetation density a(the frontal area per volume)on the flow velocity character... The aquatic plants are often found in natural rivers,and they affect the channel flow structure significantly.To study the effects of the vegetation density a(the frontal area per volume)on the flow velocity characteristics,rigid bamboo circular cylinders are chosen as the model emergent vegetation.In the experiments,the density of the vegetation takes various values while all other flow parameters are kept constant.A 3-D acoustic Doppler velocimeter(ADV)is used to measure the local flow velocities for different vegetation densities.The results show that the existence of the vegetation patch leads to an increase of the depth-averaged velocity on the right and left sides behind the vegetation patch,and it increases monotonically with the vegetation density.For different vegetation densities,the lateral distribution of the stream-wise velocity behind the vegetation patch follows approximately an S-shaped profile when a≤60 m-1,and a logarithmic profile if a>60 m-1.The vertical distribution of the stream-wise velocity along the channel varies with the vegetation density and also follows an S-shaped distribution in a certain range,with the locations and the ranges being affected by the vegetation density. 展开更多
关键词 VEGETATION density stream-wise VELOCITY depth-averaged VELOCITY lateral DISTRIBUTION longitudinal DISTRIBUTION open channel
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Influences of the diameter of the balance hole on the flow characteristics in the hub cavity of the centrifugal pump 预览
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作者 Wei Dong Wu-li Chu Zai-lun Liu 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第5期1060-1068,共9页
The diameter of the impeller balance hole in a centrifugal pump is closely related to axial force.Thus,to select the appropriate diameter of a balance hole is crucial for balancing the axial force of the centrifugal p... The diameter of the impeller balance hole in a centrifugal pump is closely related to axial force.Thus,to select the appropriate diameter of a balance hole is crucial for balancing the axial force of the centrifugal pump.After the validation of the CFD method and the grids independence study,the characteristics of flow in the hub cavity have been analyzed in 4 cases with different diameters of balance holes.The leakage rate of the liquid in the hub cavity of the centrifugal pump is calculated and compared with the test result.According to the research,when no balance hole exists,the distribution of liquid velocity in the core area of the hub cavity exhibits axial symmetry,and the circumferential velocity component is approximately 0.4 times of the impeller's rotational speed.When the balance hole exists,the distribution of liquid velocity in the hub cavity does not exhibit axial symmetry,and the circumferential velocity component is larger than 0.4 times of the impeller's rotational speed.The radial leakage velocity on the turbulent boundary layer of the pump cover will increase with the increasing diameter of the balance hole. 展开更多
关键词 Centrifugal pump balance hole HUB CAVITY CIRCUMFERENTIAL VELOCITY COMPONENT radial VELOCITY COMPONENT
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xact recession velocity and cosmic redshift based on cosmological principle and Yang-Mills gravity
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作者 Leonardo Hsu Jong-Ping Hsu 《中国物理C:英文版》 SCIE CAS CSCD 2019年第10期105-111,共7页
Based on the cosmological principle and quantum Yang-Mills gravity in the super-macroscopic limit, we obtain an exact recession velocity and cosmic redshift z, as measured in an inertial frame F≡F(t,x,y,z). For a mat... Based on the cosmological principle and quantum Yang-Mills gravity in the super-macroscopic limit, we obtain an exact recession velocity and cosmic redshift z, as measured in an inertial frame F≡F(t,x,y,z). For a matter-dominated universe, we have the effective cosmic metric tensor Gμν(t)=(B^2(t),-A^2(t),-A^2(t),-A^2(t)), A∝B∝t^1/2, where t has the operational meaning of time in F frame. We assume a cosmic action S≡Scos involving Gμν(t) and derive the ‘Okubo equation’ of motion, G^μν(t)■μS■νS-m^2=0, for a distant galaxy with mass m. This cosmic equation predicts an exact recession velocity, r=rH/[1/2+√1/4+r^2H^2/C0^2]<Co, where H=A(t)/A(t) and Co=B/A, as observed in the inertial frame F. For small velocities, we have the usual Hubble's law r≈rH for recession velocities. Following the formulation of the accelerated Wu-Doppler effect, we investigate cosmic redshifts z as measured in F. It is natural to assume the massless Okubo equation, G^μν(t)■μψe■νψe=0, for light emitted from accelerated distant galaxies. Based on the principle of limiting continuation of physical laws, we obtain a transformation for covariant wave 4-vectors between and inertial and an accelerated frame, and predict a relationship for the exact recession velocity and cosmic redshift, z=[(1+Vr)/(1-Vr^2)1/2]-1, where Vr=r/Co<1, as observed in the inertial frame F. These predictions of the cosmic model are consistent with experiments for small velocities and should be further tested. 展开更多
关键词 YANG-MILLS GRAVITY RECESSION VELOCITY speed limit of RECESSION VELOCITY REDSHIFT
A trigger-tube tracer dilution technique for determining Darcy and apparent velocities of groundwater in dug wells: A case study on phreatic aquiferous formation in Bamenda -Cameroon 预览
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作者 Akoanung Ayaba ABENDONG ENDENE Emmanuel +2 位作者 Enoh Jeanot FONGOH AKOACHERE Richard Ayuk II NJENG Napoleon Ngenge 《地下水科学与工程:英文版》 2019年第2期182-194,共13页
The need to understand flow within aquiferous formations for a complete evaluation of groundwater resource and quality control prompts the determination of groundwater velocities through well dilution technique. Well ... The need to understand flow within aquiferous formations for a complete evaluation of groundwater resource and quality control prompts the determination of groundwater velocities through well dilution technique. Well dilution techniques utilize tracer solutions after establishing an initial homogenous condition to monitor the flow rate of ambient groundwater into the wells. Application of dilution techniques in wells makes it feasible to determine the velocities of groundwater in the aquiferous formation surrounding the well. In this study, a simple trigger-tube tracer dilution technique was employed to determine the Darcy and apparent velocities of groundwater in the phreatic aquiferous formation in Bamenda, Cameroon. Eighteen (18) hand dug-wells at different locations within Bamenda were sampled by utilizing sodium chloride (NaCl) as the conservative tracer. Field estimates of groundwater flow velocities in the phreatic aquiferous formation in Bamenda reveal Darcy's groundwater velocity in the range of 0.39 m/d at Nacho to 130.64 m/d at Foncha Street and apparent velocity in the range of 0.78 m/d at Nacho to 277.86 m/d at Foncha Street. The immense variations in the velocities of groundwater indicate that the groundwater flows at different rates and directions within the aquiferous formation in Bamenda, possibly due to variations in their hydraulic conductivities. Moreover, the spatial variations in the formation types, facies changes, thickness, and layering of the aquiferous formation also contribute to the variation of velocities. Areas with low groundwater velocities are associated with a lower contaminant transport rate when compared to areas with high groundwater velocities. The findings of this study are important for assessing the rates of pollutant movement in the subsurface, as well as the effectiveness and efficacy of the trigger-tube technique in evaluating the hydraulic properties of aquiferous formations. 展开更多
关键词 Trigger-tube GROUNDWATER DARCY VELOCITY APPARENT VELOCITY Bamenda- Cameroon
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Analysis on the velocity relationship and deceleration of long-rod penetration 预览
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作者 W.J.Jiao X.W. Chen 《力学学报:英文版》 SCIE EI CAS CSCD 2019年第4期852-865,共14页
The relationship between the average penetration velocity,UˉUˉ,and the initial impact velocity, V0V0,in long-rod penetration has been studied recently. Experimental and simulation results all show the linear relatio... The relationship between the average penetration velocity,UˉUˉ,and the initial impact velocity, V0V0,in long-rod penetration has been studied recently. Experimental and simulation results all show the linear relationship between UˉUˉ and V0V0 over a wide range of V0V0 for different combinations of rod and target materials. However, the physical essence has not been fully revealed.In this paper, the Uˉ?V0Uˉ?V0relationship is profoundly analyzed using hydrodynamic model and Alekseevskii-Tate model. Especially, the explicitUˉ?V0Uˉ?V0 relationships are derived fromapproximate solutions of Alekseevskii-Tate model. Besides, the decelerationin long-rod penetration is discussed. The decelerationdegree is quantified by adeceleration index,α=2μˉ/(KΦJp)≈Ypρ?1/2p(ρ?1/2p+ρ?1/2t)V?20α=2μˉ/(KΦJp)≈Ypρp?1/2(ρp?1/2+ρt?1/2)V0?2, which is mostly related to the impact velocity, rod strength and rod/target densities. Thus, the state of penetration process can be identified and designed in experiments. 展开更多
关键词 Long-rod PENETRATION Average PENETRATION VELOCITY Initial impact VELOCITY Alekseevskii-Tate model DECELERATION
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A nonlinear model for aerodynamic configuration of wake behind horizontal-axis wind turbine 预览
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作者 Deshun LI Tao GUO +4 位作者 Rennian LI Congxin YANG Zhaoxue CHENG Ye LI Wenrui HU 《应用数学和力学:英文版》 SCIE EI CSCD 2019年第9期1313-1326,共14页
Determination of the aerodynamic configuration of wake is the key to analysis and evaluation of the rotor aerodynamic characteristics of a horizontal-axis wind turbine. According to the aerodynamic configuration, the ... Determination of the aerodynamic configuration of wake is the key to analysis and evaluation of the rotor aerodynamic characteristics of a horizontal-axis wind turbine. According to the aerodynamic configuration, the real magnitude and direction of the onflow velocity at the rotor blade can be determined, and subsequently, the aerodynamic force on the rotor can be determined. The commonly employed wake aerodynamic models are of the cylindrical form instead of the actual expanding one. This is because the influence of the radial component of the induced velocity on the wake configuration is neglected. Therefore, this model should be called a "linear model". Using this model means that the induced velocities at the rotor blades and aerodynamic loads on them would be inexact. An approximately accurate approach is proposed in this paper to determine the so-called "nonlinear" wake aerodynamic configuration by means of the potential theory, where the influence of all three coordinate components of the induced velocity on wake aerodynamic configuration is taken into account to obtain a kind of expanding wake that approximately looks like an actual one. First, the rotor aerodynamic model composed of axial (central), bound, and trailing vortexes is established with the help of the finite aspect wing theory. Then, the Biot-Savart formula for the potential flow theory is used to derive a set of integral equations to evaluate the three components of the induced velocity at any point within the wake. The numerical solution to the integral equations is found, and the loci of all elementary trailing vortex filaments behind the rotor are determined thereafter. Finally, to formulate an actual wind turbine rotor, using the nonlinear wake model, the induced velocity everywhere in the wake, especially that at the rotor blade, is obtained in the case of various tip speed ratios and compared with the wake boundary in a neutral atmospheric boundary layer. Hereby, some useful and referential conclusions are offered for the aerodynamic c 展开更多
关键词 nonlinear WAKE aerodynamic model vortex-induced VELOCITY INTEGRAL equation of vortex-induced VELOCITY horizontal-axis wind TURBINE
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一种时变分布式单位线计算方法 预览 被引量:1
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作者 孔凡哲 郭良 《水科学进展》 EI CAS CSCD 北大核心 2019年第4期477-484,共8页
为了解决由降雨强度引起的径流汇流的非线性问题,提出一种基于SCS(United States Department of Agriculture-Soil Conservation Service)流速公式的时变分布式单位线计算方法。引入参考雨强表征SCS公式中流速系数对应的水力条件。由降... 为了解决由降雨强度引起的径流汇流的非线性问题,提出一种基于SCS(United States Department of Agriculture-Soil Conservation Service)流速公式的时变分布式单位线计算方法。引入参考雨强表征SCS公式中流速系数对应的水力条件。由降雨过程的时段雨强与参考雨强的比值构成一个量纲一因子,将该因子加入SCS公式后使其能够考虑降雨对流速的影响。改进后的流速公式用于计算一次降雨过程中不同降雨时段对应的时变分布式单位线,时变分布式单位线与新安江模型的产流模块构成降雨径流模型,将模型用于裴河流域率定参考雨强。率定后的模型用于谭家河流域进行应用检验,结果显示,确定性系数大于等于0.9的洪水场次,由时不变单位线的42%增大为83%。提出的方法能够显著提高流域水文模型的降雨径流模拟能力。 展开更多
关键词 分布式单位线 流速 流速场 时变 SCS流速公式
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Study on Dynamic Characteristics of Crustal Deformation in the Yunnan Area Using GPS 预览
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作者 WANG Yan SHAO Desheng HONG Min 《中国地震研究:英文版》 CSCD 2019年第3期478-488,共11页
Based on the GPS velocity field data of 1999-2007 and 2011-2013,we used the least squares configuration method and GPS velocity profile results to synthetically analyze the dynamic evolution characteristics of crustal... Based on the GPS velocity field data of 1999-2007 and 2011-2013,we used the least squares configuration method and GPS velocity profile results to synthetically analyze the dynamic evolution characteristics of crustal deformation in the Yunnan area before and after the Wenchuan earthquake. The dynamic evolution of GPS velocity field shows that the direction is gradually changed from the south in the southern part of the SichuanYunnan block to the south-west in the southern Yunnan block and there is a clear relative motion characteristic near the block boundary fault zone. Compared with the GPS velocity of 1999-2007,the results of 2011-2013 also reflect segmental deformation characteristics of the block boundary fault zone. Southeast movement shows a significant increase,which may be related to crustal deformation adjustment after the Wenchuan earthquake. The dynamic evolution of strain parameters shows a pattern of"extension in the middle and compression at both ends"in the whole area and the distribution of deformation(shear,extension or compression)is closely related to the background motion and deformation characteristics of the main fault zone. Compared with the results of the period of 1999-2007,the extensional deformation zone of 2011-2013 is expanded eastward and southward. The compressional deformation of the eastern boundary(the Xiaojiang fault zone)of the Sichuan-Yunnan block is no longer significant,which is mainly concentrated in the northern section of the Xiaojiang fault zone and may be related to the post-seismic deformation adjustment of the Wenchuan earthquake. The GPS velocity profile results show that the left-lateral slip velocity of the Xiaojiang fault zone reduced gradually from north to south(10 mm/a-5 mm/a),and the width of the northern section is wider. The right-lateral slip rate of the Honghe fault zone is about 4 mm/a,and the deformation width is wider. The dynamic results show that the Wenchuan earthquake has little effect on the deformation modes of these two fault zones. 展开更多
关键词 Least squares configuration GPS velocity field Strain parameter GPS velocity profile
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新型泥石流平均流速测量方法的实验研究 预览
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作者 王小军 陈铭 杨航 《安阳工学院学报》 2019年第6期42-47,共6页
泥石流流速是泥石流研究领域的重要指标,在泥石流水槽模拟实验中,现有测速方法主要针对泥石流表面流速和龙头流速。为了更好地测量泥石流断面的平均流速,提出了一种新型泥石流测速装置--圆周旋转式流速装置,通过实验对比了该装置与体积... 泥石流流速是泥石流研究领域的重要指标,在泥石流水槽模拟实验中,现有测速方法主要针对泥石流表面流速和龙头流速。为了更好地测量泥石流断面的平均流速,提出了一种新型泥石流测速装置--圆周旋转式流速装置,通过实验对比了该装置与体积反算法、雷达测速仪法的测量效果,验证了该装置的有效性和适用性。水管冲击直接测试实验表明:该装置所测流速略小于由体积反算法所得的近似真实流速,这主要与装置本身的摩擦阻力有关,同时还证明了该装置可以达到较高的时间精度,0.2s时间段的速度值能较好地反应流体的平均流速。水槽实验的结果表明:该装置能连续测量断面平均流速,对流速随时间的变化和流体性质的变化均较为敏感,具有较好的灵敏度。 展开更多
关键词 泥石流 流速 水槽实验 测速装置
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基于惯性权重的蝙蝠算法 预览
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作者 杨晓琴 《太原科技大学学报》 2019年第2期123-128,共6页
蝙蝠算法是一种有效地求解单目标优化问题的启发式算法。然而,标准蝙蝠算法的速度更新方式偏向于搜索当前全局最优个体周围潜在较优个体,导致算法过早收敛。针对此缺陷,提出了基于惯性权重的蝙蝠算法,即在速度更新时添加惯性权重以改进... 蝙蝠算法是一种有效地求解单目标优化问题的启发式算法。然而,标准蝙蝠算法的速度更新方式偏向于搜索当前全局最优个体周围潜在较优个体,导致算法过早收敛。针对此缺陷,提出了基于惯性权重的蝙蝠算法,即在速度更新时添加惯性权重以改进速度更新的方向,使得种群中个体可以有效地跳出局部最优点。为验证所提算法的性能,采用了CEC2013作为测试集,PSO和标准蝙蝠算法作为对比算法。实验结果显示,所提改进算法可以有效地提升标准蝙蝠算法性能。 展开更多
关键词 蝙蝠算法 速度 过早收敛 惯性权重
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城市道路坡度和车速对机动车排放的影响 预览
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作者 郑春燕 张海 +2 位作者 郭栋 王娟 赵金宝 《河南科技大学学报:自然科学版》 CAS 北大核心 2019年第2期35-39,44,107共7页
为了分析城市道路坡度变化对机动车排放的影响,基于车载排放测试平台获取实际道路排放数据,并通过比功率反推完善数据。分析了在4个坡度区间的城市道路下,轻型车3种排放污染物(CO、HC、NOX)在不同速度区间的排放特性。研究结果表明:当... 为了分析城市道路坡度变化对机动车排放的影响,基于车载排放测试平台获取实际道路排放数据,并通过比功率反推完善数据。分析了在4个坡度区间的城市道路下,轻型车3种排放污染物(CO、HC、NOX)在不同速度区间的排放特性。研究结果表明:当车速处于20~50km/h时,每升高一个坡度区间,3种污染物的质量排放率分别提升约22.8%、23.6%、24.4%。在坡度一定的路面上,当车速处于20~40km/h时,3种污染物处于高排放状态,其质量排放率比低排放状态分别提升约64.3%、80.0%、95.0%。 展开更多
关键词 车载排放测试 城市道路坡度 速度 排放特性
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Comparative Analysis on Two Kinds of Measurement Methods of Particulate Matters in Waste Gas of Low Velocity 预览
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作者 Li Weijun Ji Guangjun +2 位作者 Yang Xianglin Zhang Xingyao Jing Yifeng 《气象与环境研究:英文版》 CAS 2019年第5期70-73,共4页
In the current waste gas sampling of fixed source,it is required that deviation of tracking rate of constant velocity sampling should not be more than 10%.When flow rate of the waste gas is less than 5 m/s,the trackin... In the current waste gas sampling of fixed source,it is required that deviation of tracking rate of constant velocity sampling should not be more than 10%.When flow rate of the waste gas is less than 5 m/s,the tracking rate can not meet this requirement.The sampling of fixed velocity can meet the requirement of particulate matter sampling on gas collection volume at low velocity.Through the comparison of two different methods for the determination of particulate matter in waste gas under the low flow velocity of flue gas,it was found that there were some differences between the fixed velocity measurement and the constant velocity measurement.The results showed that measurement result of the fixed velocity was higher than that of constant velocity measurement under low velocity.At the same time,the deviation of fixed velocity measurement was not obvious under different low velocity. 展开更多
关键词 LOW flow VELOCITY PARTICULATE MATTER Measurement COMPARATIVE analysis
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广东省潼湖生态智慧区浅层地球物理探测与地层物性分析 预览
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作者 张晓波 王成善 +3 位作者 王志辉 李海龙 李伟荣 王强茂 《地质学报》 EI CAS CSCD 北大核心 2019年第11期2935-2946,共12页
地质灾害、活动断裂、特殊岩土体和古河道等是影响城市浅层地下空间开发安全的主要地质问题,对于这些地质问题的探测主要采用地球物理无损检测方法。潼湖生态智慧区是国家生态文明建设示范区和惠州智慧城市地下空间开发中的重要区域,浅... 地质灾害、活动断裂、特殊岩土体和古河道等是影响城市浅层地下空间开发安全的主要地质问题,对于这些地质问题的探测主要采用地球物理无损检测方法。潼湖生态智慧区是国家生态文明建设示范区和惠州智慧城市地下空间开发中的重要区域,浅层地球物理探测与地层物性分析为潼湖生态智慧区城市发展及地下空间开发利用提供详细的地质、岩土和地球物理数据,是构建该地区地下空间模型的必备要素。虽然目前已经开展了针对本区域的基础地质探测研究工作,然而服务于精细地质结构与地层划分的综合地球物理研究还处于空白。针对浅层地下空间探测精细程度低和传统探测方法分辨率有限的问题,本文综合利用浅层反射波地震方法、混合源面波S波速度成像方法、三分量谐振波阻抗比值方法以及综合测井方法对该地区浅层地下空间(200m)进行了高精度地层划分和断层展布精细解释。在浅层地震反射波方法划分厚层和大尺度断层的基础上,利用主动源和被动源微脉动阵列法获得更加精细的浅层地层和构造特征,采用三分量地震频率谐振方法识别浅层土壤层分层,弥补了单一方法在不同深度范围上的探测信号低精度缺点,探讨了潼湖地区地层与地球物理的响应特征,构建了详实的地层物性和地球物理参数关系,为后续的建模提供基础数据。 展开更多
关键词 地下空间 地球物理探测 面波 速度 物性
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浓香型白酒乳酸乙酯蒸馏规律及提取影响因素的研究 预览
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作者 黄永军 谢旭 +2 位作者 洪胜 王亚庆 陈敏 《酿酒》 CAS 2019年第3期28-30,共3页
跟踪浓香生产过程,分析乳酸乙酯在不同流酒时段及不同工序时段中含量,研究其提取与润料水分、流酒温度及速度的关系,结果表明,乳酸乙酯主要存在于酒醅蒸馏的后段,且在酒样酒度接近于零时含量较高;增加润料水分对乳酸乙酯提取影响不大;... 跟踪浓香生产过程,分析乳酸乙酯在不同流酒时段及不同工序时段中含量,研究其提取与润料水分、流酒温度及速度的关系,结果表明,乳酸乙酯主要存在于酒醅蒸馏的后段,且在酒样酒度接近于零时含量较高;增加润料水分对乳酸乙酯提取影响不大;增大流速,乳酸乙酯提取含量增加;乳酸乙酯提取量随着流酒温度的增加而加大。 展开更多
关键词 乳酸乙酯 水分 温度 流速
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