This paper first analyzes the fundamental characteristics and the advantages and disadvantages in the development and utilization of land resources in China s mountainous areas. It then explores the five major strateg...This paper first analyzes the fundamental characteristics and the advantages and disadvantages in the development and utilization of land resources in China s mountainous areas. It then explores the five major strategic tasks facing the sustainable development and utilization of mountainous land resources in China. From the perspective of human-land coordination and sustainable development, the paper proposes countermeasures and recommendations for the sustainable development and utilization of land resources in China s mountainous areas.展开更多
This paper considers the swarm vigilance problem for multi-agent systems(MAS),where multiple agents are deployed within a rectangular region for perception-based vigilance.There are two main challenges,namely the task...This paper considers the swarm vigilance problem for multi-agent systems(MAS),where multiple agents are deployed within a rectangular region for perception-based vigilance.There are two main challenges,namely the task allocation for vigilance roles and the coverage planning of the perception ranges.Firstly,vigilance behavioral patterns and processes in animal populations within natural habitats are investigated.Inspired by these biological vigilance behaviors,an efficient vigilance task allocation model for MAS is proposed.Secondly,the subsequent optimization of task layouts can achieve efficient surveillance coverage with fewer agents,minimizing resource consumption.Thirdly,an improved particle swarm optimization(IPSO)algorithm is proposed,which incorporates fitness-driven adaptive inertia weight dynamics.According to simulation analysis and comparative studies,optimal parameter configurations for genetic algorithm(GA)and IPSO are determined.Finally,the results indicate the proposed IPSO's superior performance to both GA and standard particle swarm optimization(PSO)in vigilance task allocation optimization,with satisfying advantages in computational efficiency and solution quality.展开更多
The Internet of Medical Things(Io MT) is regarded as a critical technology for intelligent healthcare in the foreseeable 6G era. Nevertheless, due to the limited computing power capability of edge devices and task-rel...The Internet of Medical Things(Io MT) is regarded as a critical technology for intelligent healthcare in the foreseeable 6G era. Nevertheless, due to the limited computing power capability of edge devices and task-related coupling relationships, Io MT faces unprecedented challenges. Considering the associative connections among tasks, this paper proposes a computing offloading policy for multiple-user devices(UDs) considering device-to-device(D2D) communication and a multi-access edge computing(MEC)technique under the scenario of Io MT. Specifically,to minimize the total delay and energy consumption concerning the requirement of Io MT, we first analyze and model the detailed local execution, MEC execution, D2D execution, and associated tasks offloading exchange model. Consequently, the associated tasks’ offloading scheme of multi-UDs is formulated as a mixed-integer nonconvex optimization problem. Considering the advantages of deep reinforcement learning(DRL) in processing tasks related to coupling relationships, a Double DQN based associative tasks computing offloading(DDATO) algorithm is then proposed to obtain the optimal solution, which can make the best offloading decision under the condition that tasks of UDs are associative. Furthermore, to reduce the complexity of the DDATO algorithm, the cacheaided procedure is intentionally introduced before the data training process. This avoids redundant offloading and computing procedures concerning tasks that previously have already been cached by other UDs. In addition, we use a dynamic ε-greedy strategy in the action selection section of the algorithm, thus preventing the algorithm from falling into a locally optimal solution. Simulation results demonstrate that compared with other existing methods for associative task models concerning different structures in the Io MT network, the proposed algorithm can lower the total cost more effectively and efficiently while also providing a tradeoff between delay and energy consumption tolerance.展开更多
Introduction: The uncontrolled management of waste electrical and electronic equipment (W3E) causes respiratory problems in the handlers of this waste. The objective was to study the stains associated with respiratory...Introduction: The uncontrolled management of waste electrical and electronic equipment (W3E) causes respiratory problems in the handlers of this waste. The objective was to study the stains associated with respiratory symptoms in W3E handlers. Methods: The study was cross-sectional with an analytical focus on W3E handlers in the informal sector in Ouagadougou. A peer-validated questionnaire collected data on a sample of 161 manipulators. Results: the most common W3E processing tasks were the purchase or sale of W3E (67.70%), its repair (39.75%) and its collection (31.06%). The prevalence of cough was 21.74%, that of wheezing 14.91%, phlegm 12.50% and dyspnea at rest 10.56%. In bivariate analysis, there were significant associations at the 5% level between W3E repair and phlegm (p-value = 0.044), between W3E burning and wheezing (p-value = 0.011) and between W3E and cough (p-value = 0.01). The final logistic regression models suggested that the burning of W3E and the melting of lead batteries represented risk factors for the occurrence of cough with respective prevalence ratios of 4.57 and 4.63. Conclusion: raising awareness on the wearing of personal protective equipment, in particular masks adapted by W3E handlers, favoring those who are dedicated to the burning of electronic waste and the melting of lead could make it possible to reduce the risk of occurrence of respiratory symptoms.展开更多
In current research on task offloading and resource scheduling in vehicular networks,vehicles are commonly assumed to maintain constant speed or relatively stationary states,and the impact of speed variations on task ...In current research on task offloading and resource scheduling in vehicular networks,vehicles are commonly assumed to maintain constant speed or relatively stationary states,and the impact of speed variations on task offloading is often overlooked.It is frequently assumed that vehicles can be accurately modeled during actual motion processes.However,in vehicular dynamic environments,both the tasks generated by the vehicles and the vehicles’surroundings are constantly changing,making it difficult to achieve real-time modeling for actual dynamic vehicular network scenarios.Taking into account the actual dynamic vehicular scenarios,this paper considers the real-time non-uniform movement of vehicles and proposes a vehicular task dynamic offloading and scheduling algorithm for single-task multi-vehicle vehicular network scenarios,attempting to solve the dynamic decision-making problem in task offloading process.The optimization objective is to minimize the average task completion time,which is formulated as a multi-constrained non-linear programming problem.Due to the mobility of vehicles,a constraint model is applied in the decision-making process to dynamically determine whether the communication range is sufficient for task offloading and transmission.Finally,the proposed vehicular task dynamic offloading and scheduling algorithm based on muti-agent deep deterministic policy gradient(MADDPG)is applied to solve the optimal solution of the optimization problem.Simulation results show that the algorithm proposed in this paper is able to achieve lower latency task computation offloading.Meanwhile,the average task completion time of the proposed algorithm in this paper can be improved by 7.6%compared to the performance of the MADDPG scheme and 51.1%compared to the performance of deep deterministic policy gradient(DDPG).展开更多
The aim of teaching writing isn’t quite clear in the daily classroom teaching. This article emphasises that the aim of teaching writing isn’ t only to test, but to train. The writer analyses the problems in students...The aim of teaching writing isn’t quite clear in the daily classroom teaching. This article emphasises that the aim of teaching writing isn’ t only to test, but to train. The writer analyses the problems in students’ writing and suggests some possible ways for teachers to help students with their writing.展开更多
In this paper, a novel scheduling mechanism is proposed to handle the real-time overload problem by maximizing the cumulative values of three types of tasks： the soft, the hard and the imprecise tasks. The simulation...In this paper, a novel scheduling mechanism is proposed to handle the real-time overload problem by maximizing the cumulative values of three types of tasks： the soft, the hard and the imprecise tasks. The simulation results show that the performance of our presented mechanism in this paper is greatly improved, much better than that of the other three mechanisms： earliest deadline first （EDF）, highest value first （HVF） and highest density first （HDF）, under the same conditions of all nominal loads and task type proportions.展开更多
Based on the xu-argument, this study investigated the use of translation continuation tasks in commercial translation instruction. Forty-four second-year Business English majors at a Chinese university participated in...Based on the xu-argument, this study investigated the use of translation continuation tasks in commercial translation instruction. Forty-four second-year Business English majors at a Chinese university participated in the study. They were divided into equal-sized control and experimental groups. Members of the experimental group were asked to read Chinese-English parallel texts from a user manual, while those of the control group were asked to read the Chinese text only.Subsequently, both groups were required to translate the continued Chinese text into English. The results indicated the following: 1) the experimental group’s translated text was of significantly higher quality than that of the control group;and 2) the experimental group’s translations were well-aligned with the original text in their use of terminology, sentence structure, and stylistic features. The study concludes by suggesting that translation continuation tasks can improve commercial translation instruction and hence should be further applied in practice.展开更多
Summary: The purpose of this study was to evaluate the ergonomic risk factors associated with manual lifting tasks using surface electromyography (EMG). 13 volunteers lifted loads of 6 and 13 kg at two speeds and at t...Summary: The purpose of this study was to evaluate the ergonomic risk factors associated with manual lifting tasks using surface electromyography (EMG). 13 volunteers lifted loads of 6 and 13 kg at two speeds and at two horizontal distances in 3 different postures and three boxes of different sizes, from floor to knuckle height, performing 72 lifting tasks. For each lift, the surface electromyography signals from the erector spinae muscles, bilaterally at T_~10 and L_3, was recorded. The ergonomic risk factors associated with manual lifting tasks were evaluated by comparing the average amplitude of EMG signals from the erector spinae muscles. The EMG average amplitude for lifting the load of 13 kg was 14.3 % greater than that for lifting the load of 6 kg (t=-10.93, P<0.01). The EMG average amplitude at the site of L_3 was 10.3 % greater than that at the site of T_~10 (t=-7.98, P<0.01). The EMG average amplitude when performing “fast” lift was 5.9 %greater than the “slow” lift (t=-4.63, P<0.01). The posture of lifting affected the EMG average amplitude. It was lowest with semi-squat posture and greatest with squat posture (F=27.76, P<0.01). The result of multiple stepwise regression analysis showed that the loads of lifting, the size of box, horizontal distance, posture of lifting, the site of the spine subjected to force, lifting speed were the factors affecting the EMG average amplitude. The most significant factor was the loads of lifting, followed by the site of the spine subjected to force and the lifting speed in terms of risk. The ergonomic risk factors associated with manual lifting tasks includes the loads, posture, lifting speed, horizontal distance, the site of the spine subjected to force etc. The results of signal amplitude of EMG from the erector spinae muscles showed that semi-squat posture is the best posture for lifting tasks.展开更多
A Genetic Algorithm-Ant Colony Algorithm(GA-ACA),which can be used to optimize multi-Unit Under Test(UUT)parallel test tasks sequences and resources configuration quickly and accurately,is proposed in the paper.With t...A Genetic Algorithm-Ant Colony Algorithm(GA-ACA),which can be used to optimize multi-Unit Under Test(UUT)parallel test tasks sequences and resources configuration quickly and accurately,is proposed in the paper.With the establishment of the mathematic model of multi-UUT parallel test tasks and resources,the condition of multi-UUT resources mergence is analyzed to obtain minimum resource requirement under minimum test time.The definition of cost efficiency is put forward,followed by the design of gene coding and path selection project,which can satisfy multi-UUT parallel test tasks scheduling.At the threshold of the algorithm,GA is adopted to provide initial pheromone for ACA,and then dual-convergence pheromone feedback mode is applied in ACA to avoid local optimization and parameters dependence.The practical application proves that the algorithm has a remarkable effect on solving the problems of multi-UUT parallel test tasks scheduling and resources configuration.展开更多
In a periodic real-time system scheduled with the Earliest Deadline First (EDF) algorithm,it is necessary to compress some current tasks to avoid overloading if new task requests to run. Compressing a task means that ...In a periodic real-time system scheduled with the Earliest Deadline First (EDF) algorithm,it is necessary to compress some current tasks to avoid overloading if new task requests to run. Compressing a task means that its period is prolonged while its computation time keeps unchanged. An interesting problem is to find the earliest time to release new tasks without any deadline missing,that is,the earliest smooth insertion time. In this paper,a general frame to calculate the earliest time with multiple rounds of deadline checking is given,which shows that the checking can be done from the request time of the new tasks. A smart way is provided and proved,which takes the value of theΔchecking of the current round as the time step to the next. These techniques potentially reduce the amount of the calculation and the number of the rounds of the checking to get the earliest time. Simulation results are also given to support the conclusion.展开更多
Based on the Involvement Load Hypothesis, the present study investigated the differential effects of three post-listening output tasks(gap-filling, translation, and sentence-making) on immediate acquisition and retent...Based on the Involvement Load Hypothesis, the present study investigated the differential effects of three post-listening output tasks(gap-filling, translation, and sentence-making) on immediate acquisition and retention of such vocabulary dimensions as productive knowledge of orthography,receptive recall of meaning and form, and productive knowledge of grammatical functions. Ninety second-year English majors were divided into three groups to finish listening plus one of the postlistening tasks. The results showed that the post-listening output tasks had positive effects on immediate acquisition of productive vocabulary knowledge, partially in agreement with the Involvement Load Hypothesis. However, the effects on vocabulary knowledge retention were found to be largely inconsistent with the Involvement Load Hypothesis. The finding thus challenges this hypothesis in that involvement load is not the only determining factor and suggests that the theoretical construct of involvement load should be constructed with more caution.展开更多
English thesis writing and tutoring process is traditionally loose and open-ended. Both students and teachers enjoy much liberty in the maneuver of different steps in the whole process, which, as it were, may cause a ...English thesis writing and tutoring process is traditionally loose and open-ended. Both students and teachers enjoy much liberty in the maneuver of different steps in the whole process, which, as it were, may cause a series of problems and dissatisfactions, consequently undermining the quality and significance. This paper is intended to explore a streamlined and systematic procedure to ensure both the students and teachers are doing their bit and make due contribution to the thesis perfection.展开更多
BACKGROUND： Previous studies have analyzed cerebral activation and lateralization of cognitive functions, as well as cerebellar function with reference to high-level cognitive processing. However, there has been very...BACKGROUND： Previous studies have analyzed cerebral activation and lateralization of cognitive functions, as well as cerebellar function with reference to high-level cognitive processing. However, there has been very little research on systematization and diversification. In particular, there are no reports on cerebellar lateralization, although reliable results have been reported on cerebral lateralization. OBJECTIVE： This study analyzed cerebellar activation and lateralization in relation to verbal and visuospatial tasks using functional magnetic resonance imaging （fMRI）. DESIGN, TIME AND SETTING： A block design for fMRI observation was performed at the fMRI Laboratory, Brain Science Research Center, Korea Advanced Institute of Science and Technology from May 2006 to September 2008. PARTICIPANTS： Sixteen healthy, male, college students, aged （23.3 ± 0.5） years, and 16 healthy, male, college students, aged （21.5 ± 2.3） years, participated in the study, respectively. METHODS： Verbal and visuospatial tasks were presented while functional brain images were acquired using a 3T fMRI system. Verbal analogy testing required the subject to select the word with the same relationship as one of the given words. Verbal antonym testing required the subject to select the word with a different meaning among four words. Visuospatial tasks involved selecting a shape that corresponded to a given figure with four examples, as well as selecting a development figure of a diagram. MAIN OUTCOME MEASURES： Changes in cerebellar activation and lateralization between two cognition tasks. RESULTS： Bilateral hemisphere Iobules VI and IX, right hemisphere Iobule VIII, bilateral hemisphere Iobules Crus I, and vermis Iobule IV, V, and Vl were closely related to verbal tasks in comparison to visuospatial tasks. Conversely, bilateral hemisphere Iobules IV and V, as well as the right hemisphere Iobule VI, were closely related to visuospatial tasks compared to verbal tasks. There was no great difference between the number of activated voxels in the cerebellums during the tasks, and cerebellar lateralization was not observed. CONCLUSION： In the cerebellum, the activation region, but not lateralization, was different between verbal and visuospatial tasks.展开更多
Background:Residual torque enhancement(rTE)is the increase in torque observed during the isometric steady state following active muscle lengthening when compared with a fixed-end isometric contraction at the same musc...Background:Residual torque enhancement(rTE)is the increase in torque observed during the isometric steady state following active muscle lengthening when compared with a fixed-end isometric contraction at the same muscle length and level of neuromuscular activation.In the rTE state,owing to an elevated contribution of passive force to total force production,less active force is required,and there is a subsequent reduction in activation.In vivo studies of rTE reporting an activation reduction are often performed using a dynamometer,where participants contract against a rigid restraint,resisting a torque motor.rTE has yet to be investigated during a position task,which involves the displacement of an inertial load with positional control.Methods:A total of 12 participants(6 males,6 females;age=22.8±1.1 years,height=174.7±8.6 cm,mass=82.1±37.7 kg;mean±SD)completed torque-and position-matching tasks at 60%maximum voluntary contraction for a fixed-end isometric contraction and an isometric contraction following active lengthening of the ankle dorsiflexors.Results:There were no significant differences in activation between torque-and position-matching tasks(p=0.743),with^27%activation reduction following active lengthening for both task types(p<0.001).Conclusion:These results indicate that rTE is a feature of voluntary,position-controlled contractions.These findings support and extend previous findings of isometric torque-control conditions to position-controlled contractions that represent different tasks of daily living.展开更多
Mental task classification is one of the most important problems in Brain-computer interface.This paper studies the classification of five-class mental tasks.The nonlinear parameter of mean period obtained from freque...Mental task classification is one of the most important problems in Brain-computer interface.This paper studies the classification of five-class mental tasks.The nonlinear parameter of mean period obtained from frequency domain information was used as features for classification implemented by using the method of SVM(support vector machines).The averaged classification accuracy of 85.6% over 7 subjects was achieved for 2-second EEG segments.And the results for EEG segments of 0.5s and 5.0s compared favorably to those of Garrett's.The results indicate that the parameter of mean period represents mental tasks well for classification.Furthermore,the method of mean period is less computationally demanding,which indicates its potential use for online BCI systems.展开更多
The purpose of this study was to examine whether repetitive muscle tasks in low weight load might influence the fatigue of forearm muscles, and to identify ergonomic risk factors of forearm muscle fatigue in these tas...The purpose of this study was to examine whether repetitive muscle tasks in low weight load might influence the fatigue of forearm muscles, and to identify ergonomic risk factors of forearm muscle fatigue in these tasks. Sixteen healthy male volunteers performed eight wrist extensions in different frequency, weight and angle loads while being instructed to keep a dominant upper limb posture as constant as possible. Surface electromyograph （sEMG） was recorded from right extensors digitorium （ED）, flexor carpi radialis （FCR）, flexor carpi ulnaris （FCU） and extensor carpi ulnaris （ECU） during the task performance. Our results showed that mean power frequency （MPF） and median frequency （MF） values of ED, FCR and FCU were significantly lower （P〈0.05） at high frequency load level than at low load level. However, MPF and MF values of ED were significantly lower （P〈0.01） in higher load groups of frequency, angle and weight than in lower load groups. These results indicated that the fatigue of muscles varied in the same task, and the number-one risk factor of ECU, ED and FCR was angle load.展开更多
文摘This paper first analyzes the fundamental characteristics and the advantages and disadvantages in the development and utilization of land resources in China s mountainous areas. It then explores the five major strategic tasks facing the sustainable development and utilization of mountainous land resources in China. From the perspective of human-land coordination and sustainable development, the paper proposes countermeasures and recommendations for the sustainable development and utilization of land resources in China s mountainous areas.
基金The National Natural Science Foundation of China(62203015,62233001,62273351)The Beijing Natural Science Foundation(4242038)。
文摘This paper considers the swarm vigilance problem for multi-agent systems(MAS),where multiple agents are deployed within a rectangular region for perception-based vigilance.There are two main challenges,namely the task allocation for vigilance roles and the coverage planning of the perception ranges.Firstly,vigilance behavioral patterns and processes in animal populations within natural habitats are investigated.Inspired by these biological vigilance behaviors,an efficient vigilance task allocation model for MAS is proposed.Secondly,the subsequent optimization of task layouts can achieve efficient surveillance coverage with fewer agents,minimizing resource consumption.Thirdly,an improved particle swarm optimization(IPSO)algorithm is proposed,which incorporates fitness-driven adaptive inertia weight dynamics.According to simulation analysis and comparative studies,optimal parameter configurations for genetic algorithm(GA)and IPSO are determined.Finally,the results indicate the proposed IPSO's superior performance to both GA and standard particle swarm optimization(PSO)in vigilance task allocation optimization,with satisfying advantages in computational efficiency and solution quality.
基金supported by National Natural Science Foundation of China(Grant No.62071377,62101442,62201456)Natural Science Foundation of Shaanxi Province(Grant No.2023-YBGY-036,2022JQ-687)The Graduate Student Innovation Foundation Project of Xi’an University of Posts and Telecommunications under Grant CXJJDL2022003.
文摘The Internet of Medical Things(Io MT) is regarded as a critical technology for intelligent healthcare in the foreseeable 6G era. Nevertheless, due to the limited computing power capability of edge devices and task-related coupling relationships, Io MT faces unprecedented challenges. Considering the associative connections among tasks, this paper proposes a computing offloading policy for multiple-user devices(UDs) considering device-to-device(D2D) communication and a multi-access edge computing(MEC)technique under the scenario of Io MT. Specifically,to minimize the total delay and energy consumption concerning the requirement of Io MT, we first analyze and model the detailed local execution, MEC execution, D2D execution, and associated tasks offloading exchange model. Consequently, the associated tasks’ offloading scheme of multi-UDs is formulated as a mixed-integer nonconvex optimization problem. Considering the advantages of deep reinforcement learning(DRL) in processing tasks related to coupling relationships, a Double DQN based associative tasks computing offloading(DDATO) algorithm is then proposed to obtain the optimal solution, which can make the best offloading decision under the condition that tasks of UDs are associative. Furthermore, to reduce the complexity of the DDATO algorithm, the cacheaided procedure is intentionally introduced before the data training process. This avoids redundant offloading and computing procedures concerning tasks that previously have already been cached by other UDs. In addition, we use a dynamic ε-greedy strategy in the action selection section of the algorithm, thus preventing the algorithm from falling into a locally optimal solution. Simulation results demonstrate that compared with other existing methods for associative task models concerning different structures in the Io MT network, the proposed algorithm can lower the total cost more effectively and efficiently while also providing a tradeoff between delay and energy consumption tolerance.
文摘Introduction: The uncontrolled management of waste electrical and electronic equipment (W3E) causes respiratory problems in the handlers of this waste. The objective was to study the stains associated with respiratory symptoms in W3E handlers. Methods: The study was cross-sectional with an analytical focus on W3E handlers in the informal sector in Ouagadougou. A peer-validated questionnaire collected data on a sample of 161 manipulators. Results: the most common W3E processing tasks were the purchase or sale of W3E (67.70%), its repair (39.75%) and its collection (31.06%). The prevalence of cough was 21.74%, that of wheezing 14.91%, phlegm 12.50% and dyspnea at rest 10.56%. In bivariate analysis, there were significant associations at the 5% level between W3E repair and phlegm (p-value = 0.044), between W3E burning and wheezing (p-value = 0.011) and between W3E and cough (p-value = 0.01). The final logistic regression models suggested that the burning of W3E and the melting of lead batteries represented risk factors for the occurrence of cough with respective prevalence ratios of 4.57 and 4.63. Conclusion: raising awareness on the wearing of personal protective equipment, in particular masks adapted by W3E handlers, favoring those who are dedicated to the burning of electronic waste and the melting of lead could make it possible to reduce the risk of occurrence of respiratory symptoms.
文摘In current research on task offloading and resource scheduling in vehicular networks,vehicles are commonly assumed to maintain constant speed or relatively stationary states,and the impact of speed variations on task offloading is often overlooked.It is frequently assumed that vehicles can be accurately modeled during actual motion processes.However,in vehicular dynamic environments,both the tasks generated by the vehicles and the vehicles’surroundings are constantly changing,making it difficult to achieve real-time modeling for actual dynamic vehicular network scenarios.Taking into account the actual dynamic vehicular scenarios,this paper considers the real-time non-uniform movement of vehicles and proposes a vehicular task dynamic offloading and scheduling algorithm for single-task multi-vehicle vehicular network scenarios,attempting to solve the dynamic decision-making problem in task offloading process.The optimization objective is to minimize the average task completion time,which is formulated as a multi-constrained non-linear programming problem.Due to the mobility of vehicles,a constraint model is applied in the decision-making process to dynamically determine whether the communication range is sufficient for task offloading and transmission.Finally,the proposed vehicular task dynamic offloading and scheduling algorithm based on muti-agent deep deterministic policy gradient(MADDPG)is applied to solve the optimal solution of the optimization problem.Simulation results show that the algorithm proposed in this paper is able to achieve lower latency task computation offloading.Meanwhile,the average task completion time of the proposed algorithm in this paper can be improved by 7.6%compared to the performance of the MADDPG scheme and 51.1%compared to the performance of deep deterministic policy gradient(DDPG).
文摘The aim of teaching writing isn’t quite clear in the daily classroom teaching. This article emphasises that the aim of teaching writing isn’ t only to test, but to train. The writer analyses the problems in students’ writing and suggests some possible ways for teachers to help students with their writing.
基金supported by the Shanghai Applied Materials Foundation (Grant No.06SA18)
文摘In this paper, a novel scheduling mechanism is proposed to handle the real-time overload problem by maximizing the cumulative values of three types of tasks： the soft, the hard and the imprecise tasks. The simulation results show that the performance of our presented mechanism in this paper is greatly improved, much better than that of the other three mechanisms： earliest deadline first （EDF）, highest value first （HVF） and highest density first （HDF）, under the same conditions of all nominal loads and task type proportions.
文摘Based on the xu-argument, this study investigated the use of translation continuation tasks in commercial translation instruction. Forty-four second-year Business English majors at a Chinese university participated in the study. They were divided into equal-sized control and experimental groups. Members of the experimental group were asked to read Chinese-English parallel texts from a user manual, while those of the control group were asked to read the Chinese text only.Subsequently, both groups were required to translate the continued Chinese text into English. The results indicated the following: 1) the experimental group’s translated text was of significantly higher quality than that of the control group;and 2) the experimental group’s translations were well-aligned with the original text in their use of terminology, sentence structure, and stylistic features. The study concludes by suggesting that translation continuation tasks can improve commercial translation instruction and hence should be further applied in practice.
文摘Summary: The purpose of this study was to evaluate the ergonomic risk factors associated with manual lifting tasks using surface electromyography (EMG). 13 volunteers lifted loads of 6 and 13 kg at two speeds and at two horizontal distances in 3 different postures and three boxes of different sizes, from floor to knuckle height, performing 72 lifting tasks. For each lift, the surface electromyography signals from the erector spinae muscles, bilaterally at T_~10 and L_3, was recorded. The ergonomic risk factors associated with manual lifting tasks were evaluated by comparing the average amplitude of EMG signals from the erector spinae muscles. The EMG average amplitude for lifting the load of 13 kg was 14.3 % greater than that for lifting the load of 6 kg (t=-10.93, P<0.01). The EMG average amplitude at the site of L_3 was 10.3 % greater than that at the site of T_~10 (t=-7.98, P<0.01). The EMG average amplitude when performing “fast” lift was 5.9 %greater than the “slow” lift (t=-4.63, P<0.01). The posture of lifting affected the EMG average amplitude. It was lowest with semi-squat posture and greatest with squat posture (F=27.76, P<0.01). The result of multiple stepwise regression analysis showed that the loads of lifting, the size of box, horizontal distance, posture of lifting, the site of the spine subjected to force, lifting speed were the factors affecting the EMG average amplitude. The most significant factor was the loads of lifting, followed by the site of the spine subjected to force and the lifting speed in terms of risk. The ergonomic risk factors associated with manual lifting tasks includes the loads, posture, lifting speed, horizontal distance, the site of the spine subjected to force etc. The results of signal amplitude of EMG from the erector spinae muscles showed that semi-squat posture is the best posture for lifting tasks.
基金supported by“11th Five-year Projects”pre-research projects fund of the National Arming Department
文摘A Genetic Algorithm-Ant Colony Algorithm(GA-ACA),which can be used to optimize multi-Unit Under Test(UUT)parallel test tasks sequences and resources configuration quickly and accurately,is proposed in the paper.With the establishment of the mathematic model of multi-UUT parallel test tasks and resources,the condition of multi-UUT resources mergence is analyzed to obtain minimum resource requirement under minimum test time.The definition of cost efficiency is put forward,followed by the design of gene coding and path selection project,which can satisfy multi-UUT parallel test tasks scheduling.At the threshold of the algorithm,GA is adopted to provide initial pheromone for ACA,and then dual-convergence pheromone feedback mode is applied in ACA to avoid local optimization and parameters dependence.The practical application proves that the algorithm has a remarkable effect on solving the problems of multi-UUT parallel test tasks scheduling and resources configuration.
基金Changsha Municipal Science and Technology Foundation(K15ZD053-43).
文摘In a periodic real-time system scheduled with the Earliest Deadline First (EDF) algorithm,it is necessary to compress some current tasks to avoid overloading if new task requests to run. Compressing a task means that its period is prolonged while its computation time keeps unchanged. An interesting problem is to find the earliest time to release new tasks without any deadline missing,that is,the earliest smooth insertion time. In this paper,a general frame to calculate the earliest time with multiple rounds of deadline checking is given,which shows that the checking can be done from the request time of the new tasks. A smart way is provided and proved,which takes the value of theΔchecking of the current round as the time step to the next. These techniques potentially reduce the amount of the calculation and the number of the rounds of the checking to get the earliest time. Simulation results are also given to support the conclusion.
文摘Based on the Involvement Load Hypothesis, the present study investigated the differential effects of three post-listening output tasks(gap-filling, translation, and sentence-making) on immediate acquisition and retention of such vocabulary dimensions as productive knowledge of orthography,receptive recall of meaning and form, and productive knowledge of grammatical functions. Ninety second-year English majors were divided into three groups to finish listening plus one of the postlistening tasks. The results showed that the post-listening output tasks had positive effects on immediate acquisition of productive vocabulary knowledge, partially in agreement with the Involvement Load Hypothesis. However, the effects on vocabulary knowledge retention were found to be largely inconsistent with the Involvement Load Hypothesis. The finding thus challenges this hypothesis in that involvement load is not the only determining factor and suggests that the theoretical construct of involvement load should be constructed with more caution.
文摘English thesis writing and tutoring process is traditionally loose and open-ended. Both students and teachers enjoy much liberty in the maneuver of different steps in the whole process, which, as it were, may cause a series of problems and dissatisfactions, consequently undermining the quality and significance. This paper is intended to explore a streamlined and systematic procedure to ensure both the students and teachers are doing their bit and make due contribution to the thesis perfection.
文摘BACKGROUND： Previous studies have analyzed cerebral activation and lateralization of cognitive functions, as well as cerebellar function with reference to high-level cognitive processing. However, there has been very little research on systematization and diversification. In particular, there are no reports on cerebellar lateralization, although reliable results have been reported on cerebral lateralization. OBJECTIVE： This study analyzed cerebellar activation and lateralization in relation to verbal and visuospatial tasks using functional magnetic resonance imaging （fMRI）. DESIGN, TIME AND SETTING： A block design for fMRI observation was performed at the fMRI Laboratory, Brain Science Research Center, Korea Advanced Institute of Science and Technology from May 2006 to September 2008. PARTICIPANTS： Sixteen healthy, male, college students, aged （23.3 ± 0.5） years, and 16 healthy, male, college students, aged （21.5 ± 2.3） years, participated in the study, respectively. METHODS： Verbal and visuospatial tasks were presented while functional brain images were acquired using a 3T fMRI system. Verbal analogy testing required the subject to select the word with the same relationship as one of the given words. Verbal antonym testing required the subject to select the word with a different meaning among four words. Visuospatial tasks involved selecting a shape that corresponded to a given figure with four examples, as well as selecting a development figure of a diagram. MAIN OUTCOME MEASURES： Changes in cerebellar activation and lateralization between two cognition tasks. RESULTS： Bilateral hemisphere Iobules VI and IX, right hemisphere Iobule VIII, bilateral hemisphere Iobules Crus I, and vermis Iobule IV, V, and Vl were closely related to verbal tasks in comparison to visuospatial tasks. Conversely, bilateral hemisphere Iobules IV and V, as well as the right hemisphere Iobule VI, were closely related to visuospatial tasks compared to verbal tasks. There was no great difference between the number of activated voxels in the cerebellums during the tasks, and cerebellar lateralization was not observed. CONCLUSION： In the cerebellum, the activation region, but not lateralization, was different between verbal and visuospatial tasks.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC),Grant number:03829Infrastructure was provided by the University of Guelph start-up funding.
文摘Background:Residual torque enhancement(rTE)is the increase in torque observed during the isometric steady state following active muscle lengthening when compared with a fixed-end isometric contraction at the same muscle length and level of neuromuscular activation.In the rTE state,owing to an elevated contribution of passive force to total force production,less active force is required,and there is a subsequent reduction in activation.In vivo studies of rTE reporting an activation reduction are often performed using a dynamometer,where participants contract against a rigid restraint,resisting a torque motor.rTE has yet to be investigated during a position task,which involves the displacement of an inertial load with positional control.Methods:A total of 12 participants(6 males,6 females;age=22.8±1.1 years,height=174.7±8.6 cm,mass=82.1±37.7 kg;mean±SD)completed torque-and position-matching tasks at 60%maximum voluntary contraction for a fixed-end isometric contraction and an isometric contraction following active lengthening of the ankle dorsiflexors.Results:There were no significant differences in activation between torque-and position-matching tasks(p=0.743),with^27%activation reduction following active lengthening for both task types(p<0.001).Conclusion:These results indicate that rTE is a feature of voluntary,position-controlled contractions.These findings support and extend previous findings of isometric torque-control conditions to position-controlled contractions that represent different tasks of daily living.
基金This work was supportedin part by the National Natural Science Foundation of China(No.60271025,No.30370395)in part by the Science and Technology Depart ment of Shaanxi Province(No.2003K10-G24).
文摘Mental task classification is one of the most important problems in Brain-computer interface.This paper studies the classification of five-class mental tasks.The nonlinear parameter of mean period obtained from frequency domain information was used as features for classification implemented by using the method of SVM(support vector machines).The averaged classification accuracy of 85.6% over 7 subjects was achieved for 2-second EEG segments.And the results for EEG segments of 0.5s and 5.0s compared favorably to those of Garrett's.The results indicate that the parameter of mean period represents mental tasks well for classification.Furthermore,the method of mean period is less computationally demanding,which indicates its potential use for online BCI systems.
基金This project was supported by a grant from the German Academic Exchange Center (Deutscher Akademischer Austauschdienst,DAAD)
文摘The purpose of this study was to examine whether repetitive muscle tasks in low weight load might influence the fatigue of forearm muscles, and to identify ergonomic risk factors of forearm muscle fatigue in these tasks. Sixteen healthy male volunteers performed eight wrist extensions in different frequency, weight and angle loads while being instructed to keep a dominant upper limb posture as constant as possible. Surface electromyograph （sEMG） was recorded from right extensors digitorium （ED）, flexor carpi radialis （FCR）, flexor carpi ulnaris （FCU） and extensor carpi ulnaris （ECU） during the task performance. Our results showed that mean power frequency （MPF） and median frequency （MF） values of ED, FCR and FCU were significantly lower （P〈0.05） at high frequency load level than at low load level. However, MPF and MF values of ED were significantly lower （P〈0.01） in higher load groups of frequency, angle and weight than in lower load groups. These results indicated that the fatigue of muscles varied in the same task, and the number-one risk factor of ECU, ED and FCR was angle load.
