函数展开计数在CLUTCH方法中的初步应用

反复裂变几率(IFP)方法广泛应用于求解k特征值对连续能量核数据的灵敏度系数,然而IFP方法存在内存占用大的问题,因此CLUTCH方法被提出以解决该问题。但对于大规模问题,如压水堆全堆问题,基于网格的CLUTCH(CLUTCH-Mesh)方法存在权重函数不易收敛的问题。本文采用函数展开计数(FET)方法对CLUTCH方法中的权重函数进行统计(CLUTCH-FET)以解决该问题,函数展开计数选取的基函数是勒让德多项式。本文在蒙特卡罗粒子输运计算程序NECP-MCX中实现了IFP、CLUTCH-Mesh和CLUTCH-FET 3种方法,以IFP方法的计算结果作为参考解,对CLUTCH-Mesh和CLUTCH-FET方法的精度和效率进行了验证。数值结果表明:对于小规模问题,如Godiva和Flattop问题,CLUTCH-Mesh和CLUTCH-FET方法具有与IFP方法相当的精度,且计算效率较IFP方法更高;对于大规模问题,如AP1000全堆问题,CLUTCH-Mesh方法的计算精度下降,而CLUTCH-FET方法可保持较高的精度和计算效率,CLUTCH-FET方法的品质因子较IFP方法和CLUTCH-Mesh方法分别最多提高了5.2和6.0倍。

The clutch size,incubation behavior of Reeves’s Pheasant(Syrmaticus reevesii) and their responses to ambient temperature and precipitation

Weather conditions play a pivotal role in embryo development and parental incubation costs,potentially impacting the clutch size and incubation behavior of birds.Understanding these effects is crucial for bird conservation.Reeves’ s Pheasant(Syrmaticus reevesii) is a threatened species endemic to China,which is characterized by female-only incubation.However,there is a lack of information regarding the impact of weather conditions on clutch size and incubation behavior in this species.Using satellite tracking,we tracked 27 wild female Reeves’ s Pheasants from 2020 to 2023 in Hubei Province,China.We explored their clutch size and incubation behavior,as well as their responses to ambient temperature and precipitation.Clutch size averaged 7.75 ±1.36,had an association with average ambient temperature and average daily precipitation during the egglaying period,and was potentially linked to female breeding attempts.Throughout the incubation period,females took an average of 0.73 ±0.46 recesses every 24 h,with an average recess duration of 100.80 ±73.37 min and an average nest attendance of 92.98 ±5.27%.They showed a unimodal recess pattern in which nest departures peaked primarily between 13:00 and 16:00.Furthermore,females rarely left nests when daily precipitation was high.Recess duration and nest attendance were influenced by the interaction between daily mean ambient temperature and daily precipitation,as well as day of incubation.Additionally,there was a positive correlation between clutch size and recess duration.These results contribute valuable insights into the lifehistory features of this endangered species.

Large-brained birds lay smaller but heavier clutches

The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducing the energy consumption of reproduction or other costly tissues should compensate for the cost of a large brain.Egg production in birds requires a large proportion of the total energy budget,and a clutch mass in some bird species can outweigh the body mass of the female.To date,this hypothesis has mainly been tested in mammals and ectothermic animals such as anurans and fishes.We collated data on adult brain size,body mass and eggproduction traits such as clutch size,egg mass and annual broods from published studies,and conducted a phylogenetic comparative test of the interplay between egg-production investment and brain size evolution across bird species.After controlling for phylogenetic relationships and body size,we find a negative correlation between brain size and clutch size across 1395 species,which favored ETH.However,when egg mass was integrated in models,positive associations were detected between brain size and mass of eggs(via egg mass,clutch mass and annual total egg mass).Our results suggest that brain size trades off against egg-production only via certain aspects(e.g.,clutch size).By contrast,a positive relationship between brain size and total egg reproduction(e.g.,clutch mass and annual total egg mass) implied increased total energy budget outweighing energy allocation across bird species.Our study shows that there is no general energy trade-off between brain size and eggreproduction investment,and suggests that brain size evolution follows mixed strategies across bird species.

Study of the Judder Characteristics of Friction Material for an Automobile Clutch and Test Verification

The friction judder characteristics during clutch engagement have a significant influence on the NVH of a driveline.In this research,the judder characteristics of automobile clutch friction materials and experimental verification are studied.First,considering the stick-slip phenomenon in the clutch engagement process,a detailed 9-degrees-of-freedom(DOF)model including the body,each cylinder of the engine,clutch and friction lining,torsional damper,transmission and other driveline parts is established,and the calculation formula of friction torque in the clutch engagement process is determined.Second,the influence of the friction gradient characteristics on the amplification or attenuation of the automobile friction judder is analyzed,and the corresponding stability analysis and the numerical simulation of different friction gradient values are carried out with MATLAB/Simulink software.Finally,judder bench test equipment and a corresponding damping test program are developed,and the relationship between the friction coefficient gradient characteristics and the system damping is analyzed.After a large number of tests,the evaluation basis of the test is determined.The research results show that the friction lining with negative gradient characteristics of the friction coefficient will have a judder signal.When the friction gradient value is less than-0.005 s/m,the judder signal of the measured clutch cannot be completely attenuated,and the judder phenomenon occurs.When the friction gradient is greater than-0.005 s/m,the judder signal can be significantly suppressed and the system connection tends to be stable.

解读竞赛压力下的运动表现:一个“Clutch”视角的运动能力初探

"Clutch"是一种与"Choking"典型相反的现象,主要描述运动员在比赛关键时刻的完美表现。基于"Clutch"表现,从现象学的角度,讨论压力下运动能力的发挥,并分析"Clutch"运动员的能力表现特征,旨在为优秀运动员的训练和选拔提供理论依据。研究认为,竞赛压力下的运动表现存在极性现象,"Choking"反映的是负性运动表现,而"Clutch"反映的是正性运动表现。从特征解释上讲,"Choking"表述为情景的运动表现,而"Clutch"则是特质的运动表现。"Clutch"反映了运动员在压力下展示技术的能力,一般发生在优秀运动员身上。通过"Clutch"运动表现的案例分析,结合相关研究成果,认为"Clutch"运动员是存在的,并提出了"Clutch"运动员的能力表现解释模型。该模型主要包括"专项运动能力"、"压力认知应对能力"和"运动员人格"3个方面。

Modeling and Experimental Study for Automotive Dry Clutch Sliding Noise

Automotive dry clutches have been found to produce a low frequency sliding noise in many applications,which challenges the ride comfort of vehicles.In order to study this clutch sliding noise,a detailed finite element model including both a pressure plate assembly and a driven plate assembly was developed.Based on this model,a complex eigenvalue analysis is performed in this research.The effect of several major factors on the clutch sliding noise,such as the coefficient of friction,the clamping force,the geometric imperfection of the friction plate,and the thermal deformation of the pressure plate,were investigated numerically.A vehicle road test with clutch sliding noise was conducted for several different conditions.The leading frequencies of the clutch sliding noise in the testing were obtained and compared with the frequencies predicted by the numerical model.The simulation results show the same tendency as the road test.It is found that the clutch sliding noise can be reduced by decreasing the coefficient of friction.With the presence of the surface bumping of the friction plate,the propensity of the clutch sliding noise greatly increases and the corresponding squeal frequencies fall into the range lower than 1 kHz.With the consideration of the thermally introduced deformation of the clutch pressure plate,the possibility of clutch sliding noise is significantly reduced.It is concluded that the model with the incorporation of the thermal deformation of the pressure plate is more effective for the frequency prediction of clutch sliding noise.

Choking与Clutch运动员的自我感知、状态焦虑及应对方式质性研究——以乒乓球项目为例

压力通常被认为是影响工作的重要因素,“Choking”与“Clutch”是常见的压力极性化表现。以乒乓球项目为例,通过对运动员出现“Choking”或“Clutch”时的自我感知、状态焦虑及应对方式进行质性研究,解读两种比赛状态的表现特征及诱因,并对减少“Choking”现象的产生,增加“Clutch”的发生概率提出建议。

Experimental Research and Mathematical Model of Drag Torque in Single-plate Wet Clutch

Reduction of drag torque is one of important potentials to improve transmission efficiency.Existing mathematical model of drag torque was not accurate to predict the decrease after oil film shrinking because of the difficulty in modeling the flow pattern between two plates.Flow pattern was considered as laminar flow and full oil film in the gap between two plates in traditional model.Subsequent equivalent circumferential degree model presented an improvement in oil film shrinking due to centrifugal force,but was also based on full oil film in the gap,which resulted difference between model prediction and experimental data.The objective of this paper is to develop an accurate mathematical model for the above problem by using experimental verification.An experimental apparatus was set up to test drag torque of disengaged wet clutch consisting of single friction and separate plate.A high speed camera was used to record the flow pattern through transparent quartz disk plate.The visualization of flow pattern in the clearance was investigated to evaluate the characteristics of oil film shrinking.Visual test results reveal that the oil film begins to shrink from outer radius to inner radius at the stationary plate and only flows along the rotating plate after shrinking.Meanwhile,drag torque decreases sharply due to little contact area between the stationary plate and the oil.A three-dimensional Navier-Stokes （N-S） equation based on laminar flow is presented to model the drag torque.Pressure distributions in radial and circumferential directions as well as speed distributions are deduced.The model analysis reveals that the acceleration of flow in radial direction caused by centrifugal force is the key reason for the shrinking at the constant feeding flow rate.An approach to descript flow pattern was presented on the basis of visual observation.The drag torque predicted by the model agrees well with test data for non-grooved wet clutch.The proposed model enhances the precision for predicting drag torque,and lays down a framework on which some subsequent models are developed.

“Clutch”运动员特征的概念构图

研究基于王进等(2013)的"Clutch"运动员能力特征假设模型,运用概念构图的数据分析方法,验证"Clutch"运动员的结构解释要素。被试为6名高级教练员、6名优秀运动员和6名运动训练方面的专家,通过一对一的深度访谈,收集数据作为分析素材。然后按照创建分析单元、分类、多维定标、聚类分析、完成概念构图和解释概念构图的顺序进行分析。结果支持了王进等的"Clutch"运动员的结构要素解释假设模型,并且发现解释模型的3个要素可具体分解为压力认知敏感度、压力应对能力、心智能力、身体与技战术能力、心理敢为性、态度积极性、心理坚韧性和自信8个维度。并进一步讨论了其概念的内涵。

OPTIMAL CONTROL APPLIED IN AUTOMATIC CLUTCH ENGAGEMENTS OF VEHICLES

Start-up working condition is the key to the research of optimal engagementof automatic clutch for AMT. In order to guarantee an ideal dynamic performance of the clutchengagement, an optimal controller is designed by considering throttle angle, engine speed, gearratio, vehicle acceleration and road condition. The minimum value principle is also introduced toachieve an optimal dynamic performance of the nonlinear system compromised in friction plate wearand vehicle drive quality. The optimal trajectory of the clutch engagement can be described in theform of explicit and analytical expressions and characterized by the deterministic and accuratecontrol strategy in stead of indeterministic and soft control techniques which need thousands ofexperiments. For validation of the controller, test work is carried out for the automated clutchengagements in a commercial car with an traditional mechanical transmission, a hydraulic actuator, agroup of sensors and a portable computer system. It is shown through experiments that dynamicbehaviors of the clutch engagement operated by the optimal control are more effective and efficientthan those by fuzzy control.

Adaptive Clutch Engaging Process Control for Automatic Mechanical Transmission

Based on detail analysis of clutch engaging process control targets and adaptive demands, a control strategy which is based on speed signal, different from that of based on main clutch displacement signal, is put forward. It considers both jerk and slipping work which are the most commonly used quality evaluating indexes of vehicle starting phase. The adaptive control system and its reference model are discussed profoundly. Taking the adaptability to different starting gears and different road conditions as examples, some proving field test records are shown to illustrate the main clutch adaptive control strategy at starting phase. Proving field test gives acceptable results.

Design and analysis of logarithmic spiral type sprag one-way clutch

A complete mathematical model for logarithmic spiral type sprag one-way clutch design and analysis is given.It assumes that the motion of all clutch components can be expressed by a model of epicyclic gearing.It takes advantage of Hunt-Crossley contact impact theory to calculate the contact forces between sprags and races,and it can be used for optimization of design and comparison with other types of sprag clutches.A good deal of analysis shows that the parameters of the steady windup angle,the steady contact force,the natural frequency and natural cycle of clutch have nothing to do with the initial velocity of outer race,while the parameters of the maximum transient windup angle,the maximum transient impact force and the steady engagement time increase linearly in the mode of engaging operation of clutch.It is also shown that the strut angle has great influence on the dynamic engagement performance of clutch.The parameters of the steady windup angle,the maximum transient windup angle,the steady engaging time,the steady contact force,the maximum transient impact force and the natural cycle of clutch decrease linearly nearly with the inner strut angle,while the natural frequency of the system increases linearly with the inner strut angle.

STUDY ON CONTROL STRATEGY OF CLUTCH STARTING FOR CAR WITH A METAL PUSHING BELT-PLANETARY GEAR CONTINUOUSLY VARIABLE TRANSMISSION SYSTEM

The automatic control of clutch starting in car with a metal pushingbelt-planetary gear continuously variable transmission (CVT) is a complex problem. A suited controlstrategy is required to realize quick and smooth start. A simulation state space equation isestablished on clutch staring control of a car with CVT by bond graph theory. According to the fuzzycontrol method with the expert system, a fuzzy control system of car starting process to weaken thejerk motion is introduced. The simulation results indicate that the jerk motion of clutch startingis below 10 m/s^3.

Mathematical Model and Experiment Validation of Fluid Torque by Shear Stress under Influence of Fluid Temperature in Hydro-viscous Clutch

The current design of hydro-viscous clutch（HVC） in tracked vehicle fan transmission mainly focuses on high-speed and high power. However, the fluid torque under the influence of fluid temperature can not be predicted accurately by conventional mathematical model or experimental research. In order to validate the fluid torque of HVC by taking the viscosity-temperature characteristic of fluid into account, the test rig is designed. The outlet oil temperature is measured and fitted with different rotation speed, oil film thickness, oil flow rate, and inlet oil temperature. Meanwhile, the film torque can be obtained. Based on Navier-Stokes equations and the continuity equation, the mathematical model of fluid torque is proposed in cylindrical coordinate. Iterative method is employed to solve the equations. The radial and tangential speed distribution, radial pressure distribution and theoretical flow rate are determined and analyzed. The models of equivalent radius and fluid torque of friction pairs are introduced. The experimental and theoretical results indicate that tangential speed distribution is mainly determined by the relative rotating speed between the friction plate and the separator disc. However, the radial speed distribution and pressure distribution are dominated by pressure difference at the lower rotating speed. The oil film fills the clearance and the film torque increases with increasing rotating speed. However, when the speed reaches a certain value, the centrifugal force will play an important role on the fluid distribution. The pressure is negative at the outer radius when inlet flow rate is less than theoretical flow, so the film starts to shrink which decreases the film torque sharply. The theoretical fluid torque has good agreement with the experimental data. This research proposes a new fluid torque mathematical model which may predict the film torque under the influence of temperature more accurately.

Research on Drag Torque Prediction Model for the Wet Clutches

Considering the surface tension effect and centrifugal effect, a mathematical model based on Reynolds equation for predicting the drag torque of disengage wet clutches is presented. The model indicates that the equivalent radius is a function of clutch speed and flow rate. The drag torque achieves its peak at a critical speed. Above this speed, drag torque drops due to the shrinking of the oil film. The model also points out that viscosity and flow rate effects on drag torque. Experimental results indicate that the model is reason-able and it performs well for predicting the drag torque peak.

Clinical outcomes of Clutch Cutter endoscopic submucosal dissection for older patients with early gastric cancer

AIM To evaluate the clinical outcome of endoscopic submucosal dissection using the Clutch Cutter(ESDCC) in older patients. METHODS We reviewed 232 consecutive patients with early gastric cancer who underwent ESDCC between June 2010 and February 2014 at Aso Iizuka Hospital. We divided patients into two groups according to age: Older patients(> 80 years, n = 64) and non-older patients(≤ 80 years, n = 168). We retrospectively compared the prevalence rates of pre-existing comorbidities, anticoagulant therapy, en bloc resection, mean duration of hospitalization, incidence of ESDCC-related complications, change in performance status(PS) before and after ESDCC, and financial cost of admission. RESULTS The older group comprised 64 patients with a mean age of 84.1 years, and the non-older group comprised 168 patients with a mean age of 69.5 years. Older patients had significantly more pre-existing comorbidities than did non-older patients, specifically heart disease(P < 0.05). The en bloc resection rate in non-older patients was significantly higher than that in older patients(100% vs 95.3%, P = 0.02). There were no significant differences between the older and non-older groups in the incidence of ESDCC-related complications(i.e., postoperative bleeding and perforation) and the post-ESDCC change in PS. There were also no significant differences between the older and non-older groups in the mean duration of hospitalization(11.4 and 10.7 d, respectively) and financial cost of admission(657040 JPY and 574890 JPY, respectively).CONCLUSION ESDCC has a good clinical outcome in older patients.

Geographic Variation in Clutch and Egg Size for the Lizard Phrynocephalus przewalskii(Squamata:Agamidae)

In order to tease apart proximate vs. ultimate sources of variation in reproductive strategy, studies have increasingly focused on populations rather than species as the unit of interest. The reproductive parameters of Phrynocephalus przewalskii （Agamidae） in different populations within the same phylogenetic clade were compared in this study. Female SVL, clutch size, egg volume and clutch volume varied significantly among populations. With increase in latitude, clutch size increased, while egg size decreased. Relatively fewer but larger eggs were produced with increasing of population density. Food availability had positive effects on clutch size, but no effect on egg size. Our result indicated that latitude, food availability and population density may be the proximate factors affecting the reproductive parameters ofP. przewalskii.

RELIABILITY AND OPTIMIZATION DESIGN OF NEW ROLLER ORIENTATION CLUTCH

The mechanical reliability and optimization theory on the method ofreliability-optimization design for the new roller orientation clutch is provided. The result ofreliability-optimization design is compared with the result of the conventional design method.

Clutch Cutter knife efficacy in endoscopic submucosal dissection for early gastric neoplasms

AIM To compare the outcomes of endoscopic submucosal dissection(ESD) for gastric neoplasms using Clutch Cutter(ESD-C) or other knives(ESD-O).METHODS This was a single-center retrospective study. Gastric neoplasms treated by ESD between April 2016 and October 2017 at Kitakyushu Municipal Medical Center were reviewed. Multivariate analyses and propensity score matching were used to reduce biases. Covariates included factors that might affect outcomes of ESD, including age, sex, underlying disease, anti-thrombotic drugs use, tumor location, tumor position, tumor size, tumor depth, tumor morphology, tumor histology, ulcer(scar), and operator skill. The treatment outcomes were compared among two groups. The primary outcome was ESD procedure time. Secondary outcomes were en bloc, complete, and curative resection rates, and adverse events rates including perforation and delayed bleeding.RESULTS A total of 155 patients were included in this study; 44 pairs were created by propensity score matching. Background characteristics were quite similar among two groups after matching. Procedure time was significantly shorter for ESD-C(median; 49 min) than for ESD-O(median; 88.5 min)(P < 0.01). However, there was no significant difference in treatment outcomes between ESD-C and ESD-O including en bloc resection rate(100% in both groups), complete resection rate(100% in both groups), curative resection rate(86.4% vs 88.6%, P = 0.730), delayed bleeding(2.3% vs 6.8%, P = 0.62) and perforation(0% in both groups).CONCLUSION ESD-C achieved shorter procedure time without an increase in complication risk. Therefore, ESD-C could become an effective ESD option for gastric neoplasms.

Estimating the clutch transmitting torque during HEV mode-switch based on the Kalman filter

A power train dynamics model of a coaxial parallel hybrid electric vehicle （HEV） was built for different clutch operating states. With the state vector constituted by the motor rotation speed and the clutch transmitting torque at two successive time steps, a discrete state space model for estimating the clutch transmitting torque was built, and the Kalman filtering algorithm was used to estimate the clutch transmitting torque. The Matlab/Simulink was employed to simulate the clutch transmitting torque for two mode-switch processes. Estimation errors were analyzed through compa- ring the estimated and simulated values of the clutch torque. Impact of the noise covariance and the sample time on clutch torque estimation errors were explored. The results show that the developed estimation method can be used to estimate the clutch transmitting torque for HEV with good accura- cy. The results are useful for torque direct control of automatic diaphragm clutches.