Robotic lawn mowers available in markets are much more complicated with high cost, hence, a new robot is designed in the research. In detail, the control system is made up of Arduino Mega2560 and 11 sensors and the ro...Robotic lawn mowers available in markets are much more complicated with high cost, hence, a new robot is designed in the research. In detail, the control system is made up of Arduino Mega2560 and 11 sensors and the robot works with four wheels (two front and back wheels) driven by an electric motor. Furthermore, the platform of lawn-mowing is designed semicircle, equipped with three small high- speed and low-power electric motors; the cutting distance is determined by width of motherboard. In addition, the hardware of the system is made up of circuit control and working machines, of which the former includes a single chip unit, a wireless remote control, a sensor unit, an infrared array module, a driving module of electric motor, a display unit and a power source; the latter includes a mowing platform and a sensor window. In addition, the related software is programmed using C language and modular programming involving PWM program, Hall sensor program, liquid-crys- tal display, tilt program, supersonic sounding program, infrared obstacle-avoidance program, parking program, and remote control program. After hardware was adjust- ed, the robotic lawn mower was tested for multiple times in a standard lawn, and a satisfied effect was achieved.展开更多
Abnormal movement states for a mobile robot were identified by four multi-layer perceptron. In the presence ot abnormality, avoidance strategies were designed to guarantee the safety of the robot. Firstly, the kinemat...Abnormal movement states for a mobile robot were identified by four multi-layer perceptron. In the presence ot abnormality, avoidance strategies were designed to guarantee the safety of the robot. Firstly, the kinematics of the normal and abnormal movement states were exploited, 8 kinds of features were extracted. Secondly, 4 multi-layer pereeptrons were employed to classify the features for four 4-driving wheels into 4 kinds of states, i.e. normal, blocked, deadly blocked, and slipping. Finally, avoidance strategies were designed based on this. Experiment results show that the methods can identify most abnormal movement states and avoid the abnormality correctly and timely.展开更多
This paper proposes an intelligent low-thrust orbit phasing control method for multiple spacecraft by simultaneously considering fuel optimization and collision avoidance. Firstly,the minimum-fuel orbit phasing contro...This paper proposes an intelligent low-thrust orbit phasing control method for multiple spacecraft by simultaneously considering fuel optimization and collision avoidance. Firstly,the minimum-fuel orbit phasing control database is generated by the indirect method associated with the homotopy technique. Then,a deep network representing the minimum-fuel solution is trained. To avoid collision for multiple spacecraft,an artificial potential function is introduced in the collision-avoidance controller. Finally,an intelligent orbit phasing control method by combining the minimum-fuel neural network controller and the collision-avoidance controller is proposed. Numerical results show that the proposed intelligent orbit phasing control is valid for the multi-satellite constellation initialization without collision.展开更多
This paper focuses on the relationship between firm risk profile, agency incentives and corporate performance using correlation study and cross-sectional approach. We conceptualise firm risk profile using the balanced...This paper focuses on the relationship between firm risk profile, agency incentives and corporate performance using correlation study and cross-sectional approach. We conceptualise firm risk profile using the balanced score card and differ from previous studies, on the above variables, by capturing the perceptual sets of strategic leadership of Ugandan firms who are members of corporate governance of Uganda. We post a significant negative relationship between firm risk profile and corporate performance, a significant negative relationship between firm risk profile and agency incentives and a positive relationship between agency incentives and corporate performance By employing Joseph and Scott (2006)'s utilization of the balanced score card to identify the four forms of firm risk (namely, financial, customer, internal and learning and growth risks), our results support the application of agency theory as a relevant theoretical framework for dealing with managers who are risk averse.展开更多
For real-time and distributed features of multi-robot system,the strategy of combining the improved artificial potential field method and the rules based on priority is proposed to study the collision avoidance planni...For real-time and distributed features of multi-robot system,the strategy of combining the improved artificial potential field method and the rules based on priority is proposed to study the collision avoidance planning in multi-robot systems. The improved artificial potential field based on simulated annealing algorithm satisfactorily overcomes the drawbacks of traditional artificial potential field method,so that robots can find a local collision-free path in the complex environment. According to the movement vector trail of robots,collisions between robots can be detected,thereby the collision avoidance rules can be obtained. Coordination between robots by the priority based rules improves the real-time property of multi-robot system. The combination of these two methods can help a robot to find a collision-free path from a starting point to the goal quickly in an environment with many obstacles. The feasibility of the proposed method is validated in the VC-based simulated environment.展开更多
Contrary to the conventional wisdom which suggests that a perfectly rational subject with risk-averse attitude should never gamble, this paper provides a vivid example in our real economy for people to expect a positi...Contrary to the conventional wisdom which suggests that a perfectly rational subject with risk-averse attitude should never gamble, this paper provides a vivid example in our real economy for people to expect a positive return to gamble Within the existing literature, scholars have proposed different reasons to explain why an original risk-averse person would start to gamble, with the implicit assumption that the expected payoff of a bet is always lower than its cost. In contrast, our paper discusses when and why a risk-averse person could bet strategically with a positive expected return; in particular, we used field data in Hong Kong to illustrate a vivid scenario for positive expected return in gambling.展开更多
The article assesses the determinants of farmers' decisions to participate in organic farming, eliciting farmers risk preferences and empirically analysing farmer's sources of risk and risk management strategies. Th...The article assesses the determinants of farmers' decisions to participate in organic farming, eliciting farmers risk preferences and empirically analysing farmer's sources of risk and risk management strategies. The ordered probit results indicate that older farmers, who are less risk averse and reside in the sub-ward Ogagwini, Ezigani and Hwayi were more likely to be certified organic. Similarly, the propensity to adopt organic farming is positively correlated to household size, livestock ownership, asset base and tenure security. At higher pay-offs, farmers were intermediate to moderately risk-averse, with little variation according to personal characteristics. In general, price, production and financial risks were perceived as important sources of risk. Seven principal components, explaining 66.13% of the variation were extracted. Socio-economic factors having a significant effect on the various sources of risk were age, gender, education, location, information access and risk taking ability. The dimensions of risk strategies were named as diversification, precautionary savings and social networks. Results provide practical insights for policy changes relevant in motivating the adoption of organic practices, increasing smallholder farmers' capacity to manage risk and driving growth in the organic food market.展开更多
Employee stock options (ESOs) have become an integral component of compensation in the US. In view of their significant cost to firms, the Financial Accounting Standards Board (FASB) has mandated expensing ESOs si...Employee stock options (ESOs) have become an integral component of compensation in the US. In view of their significant cost to firms, the Financial Accounting Standards Board (FASB) has mandated expensing ESOs since 2004. The main difficulty of ESO valuation lies in the uncertain timing of exercises, and a number of contractual restrictions of ESOs further complicate the problem. We present a valuation framework that captures the main characteristics of ESOs. Specifically, we incorporate the holder's risk aversion, and hedging strategies that include both dynamic trading of a correlated asset and static positions in market-traded options. Their combined effect on ESO exercises and costs are evaluated along with common features like vesting periods, job termination risk and multiple exercises. This leads to the study of a joint stochastic control and optimal stopping problem. We find that ESO values are much less than the corresponding Black-Scholes prices due to early exercises, which arise from risk aversion and job termination risk; whereas static hedges induce holders to delay exercises and increase ESO costs.展开更多
The social security fund investment operations of the social security system of a country or even the whole economy has a very important role in recent years, although China's social security fund management has made...The social security fund investment operations of the social security system of a country or even the whole economy has a very important role in recent years, although China's social security fund management has made great progress, but China's social security fund investment operations in increasing the value of the pursuit of this goal, while also facing tremendous pressure. After years of practice of reform, China's old-age, unemployment and medical insurance and minimum living focused on the social security system has taken shape, but also the corresponding social security fund was established. Part of the problems of social security funds and other investment operations are increasingly apparent. How to achieve the social security fund is necessary to ensure payment, but also realize the accumulation, it is necessary to increase the value, but also to avoid risks, it has become an urgent task of China's reform and development. Social Security Fund Investment Management became the central task of the Social Security System.展开更多
This paper investigates a risk-averse inventory model by balancing the expected profit and conditional value-at-risk (CVaR) in a newsvendor model setting. We find out that: i) The optimal order quantity is increas...This paper investigates a risk-averse inventory model by balancing the expected profit and conditional value-at-risk (CVaR) in a newsvendor model setting. We find out that: i) The optimal order quantity is increasing in the shortage cost for both the CVaR only criterion and the tradeoff objective, ii) For the case of zero shortage cost, the optimal order quantity to the CVaR criterion or tradeoff objective is increasing in the selling price, respectively. However, it may not be monotonic in the selling price when incorporating a substantial shortage cost. Moreover, it may be larger or less than the risk-neutral solution, iii) Under the tradeoff objective function, although the optimal order quantity for the model without shortage cost is increasing in the weight put on the expected profit, this property may not be true in general for the model with a substantial shortage cost. Some numerical examples are conducted to verify our results and observations.展开更多
This paper develops a kind of generalized double-sided moral hazard model of contract choice with Cobb-Douglas technology in a frame of principal-agent theory. The two parties, the principal and the agent, generally h...This paper develops a kind of generalized double-sided moral hazard model of contract choice with Cobb-Douglas technology in a frame of principal-agent theory. The two parties, the principal and the agent, generally have different levels of production efficiency, relative importance factor and are risk-averse or risk-neutral. Using this model, we formally prove that the optimal contract maximizes the output net of the disutility of both the parties and carry out some simulations exercise under two special cases which help explain the double-sided moral hazard issues. By focusing on production efficiency, relative importance factor and risk attitude respectively, this paper analyzes the properties of optimal contracts under three cases.展开更多
Both eukaryotic and prokaryotic pathogens infect the host stably via an immune evasion mecha- nism termed mutually exclusive expression. Nowadays, little is known about this epigenetic mechanism, largely limiting th...Both eukaryotic and prokaryotic pathogens infect the host stably via an immune evasion mecha- nism termed mutually exclusive expression. Nowadays, little is known about this epigenetic mechanism, largely limiting the understanding of pathogenesis of many bacterial, fungal and protozoan pathogens and therefore the development of novel drugs and vaccines. In the most severe malaria parasite, Plasrnodiurn falciparum, there is a major virulence gene family termed vat, by which the variant antigen PfEMP1 is encoded and expressed on the surface of parasite-infected erythrocytes. Each parasite carries about 60 anti- genically various vat genes, however, only one of which is expressed at a given time during infection. P. falciparum expresses PfEMP1s in this clonally variant manner to bind to different human endothelial re- ceptors, allowing the infected erythrocytes to sequester in tissues to escape the host's immune response in- cluding spleen killing and humoral immunity. At present, the mechanism of mutually exclusive expression of the var gene family remains largely unknown, even though there is increasing evidence suggesting im- portant roles of the epigenetic regulation involved in vat gene expression. In addition, epigenetic factors were also found in association with transcriptional regulation of other antigenic variant gene families in P. falciparum. In this paper, we review the current understanding of epigenetic regulations of P. falcipa- rum virulence genes with particular views toward the design of novel vaccines, drugs, and diagnosis to ma- laria.展开更多
Obstacle avoidance is quite an important issue in the field of legged robotic applications, such as rescuing and detecting in complicated environment. Most related researchers focused on the legged robot’s gait gener...Obstacle avoidance is quite an important issue in the field of legged robotic applications, such as rescuing and detecting in complicated environment. Most related researchers focused on the legged robot’s gait generation after ssuming that obstacles have been detected and the walking path has been given. In this paper we propose and validate a novel obstacle avoidance framework for a six-legged walking robot Hexapod-III in unknown environment. Throughout the paper we highlight three themes: (1) The terrain map modeling and the obstacle detection; (2) the obstacle avoidance path planning method; (3) motion planning for the legged robot. Concretely, a novel geometric feature grid map (GFGM) is proposed to describe the terrain. Based on the GFGM, the obstacle detection algorithm is presented. Then the concepts of virtual obstacles and safe conversion pose are introduced. Virtual obstacles restrict the robot to walk on the detection terrain. A safe path based on Bezier curves, passing through safe conversion poses, is obtained by minimizing a penalty function taking into account the path length subjected to obstacle avoidance. Thirdly, motion planning for the legged robot to walk along the generated path is discussed in detail. At last, we apply the proposed framework to the Hexapod-III robot. The experimental result shows that our methodology allows the robot to walk safely without encountering with any obstacles in unknown environment.展开更多
基金Supported by National Natural Science Foundation of China (11275164)~~
文摘Robotic lawn mowers available in markets are much more complicated with high cost, hence, a new robot is designed in the research. In detail, the control system is made up of Arduino Mega2560 and 11 sensors and the robot works with four wheels (two front and back wheels) driven by an electric motor. Furthermore, the platform of lawn-mowing is designed semicircle, equipped with three small high- speed and low-power electric motors; the cutting distance is determined by width of motherboard. In addition, the hardware of the system is made up of circuit control and working machines, of which the former includes a single chip unit, a wireless remote control, a sensor unit, an infrared array module, a driving module of electric motor, a display unit and a power source; the latter includes a mowing platform and a sensor window. In addition, the related software is programmed using C language and modular programming involving PWM program, Hall sensor program, liquid-crys- tal display, tilt program, supersonic sounding program, infrared obstacle-avoidance program, parking program, and remote control program. After hardware was adjust- ed, the robotic lawn mower was tested for multiple times in a standard lawn, and a satisfied effect was achieved.
基金Project (60234030) supported by the National Natural Science Foundation of China
文摘Abnormal movement states for a mobile robot were identified by four multi-layer perceptron. In the presence ot abnormality, avoidance strategies were designed to guarantee the safety of the robot. Firstly, the kinematics of the normal and abnormal movement states were exploited, 8 kinds of features were extracted. Secondly, 4 multi-layer pereeptrons were employed to classify the features for four 4-driving wheels into 4 kinds of states, i.e. normal, blocked, deadly blocked, and slipping. Finally, avoidance strategies were designed based on this. Experiment results show that the methods can identify most abnormal movement states and avoid the abnormality correctly and timely.
基金supported in part by the National Natural Science Foundation of China (No. 11772104)in part by the Key Research and Development Plan of Heilongjiang Province(No. GZ20210120)in part by the Fundamental Research Funds for the Central Universities。
文摘This paper proposes an intelligent low-thrust orbit phasing control method for multiple spacecraft by simultaneously considering fuel optimization and collision avoidance. Firstly,the minimum-fuel orbit phasing control database is generated by the indirect method associated with the homotopy technique. Then,a deep network representing the minimum-fuel solution is trained. To avoid collision for multiple spacecraft,an artificial potential function is introduced in the collision-avoidance controller. Finally,an intelligent orbit phasing control method by combining the minimum-fuel neural network controller and the collision-avoidance controller is proposed. Numerical results show that the proposed intelligent orbit phasing control is valid for the multi-satellite constellation initialization without collision.
文摘This paper focuses on the relationship between firm risk profile, agency incentives and corporate performance using correlation study and cross-sectional approach. We conceptualise firm risk profile using the balanced score card and differ from previous studies, on the above variables, by capturing the perceptual sets of strategic leadership of Ugandan firms who are members of corporate governance of Uganda. We post a significant negative relationship between firm risk profile and corporate performance, a significant negative relationship between firm risk profile and agency incentives and a positive relationship between agency incentives and corporate performance By employing Joseph and Scott (2006)'s utilization of the balanced score card to identify the four forms of firm risk (namely, financial, customer, internal and learning and growth risks), our results support the application of agency theory as a relevant theoretical framework for dealing with managers who are risk averse.
基金Sponsored by the Science Foundation for Youths of Heilongjiang province (Grant No.QC08C05)
文摘For real-time and distributed features of multi-robot system,the strategy of combining the improved artificial potential field method and the rules based on priority is proposed to study the collision avoidance planning in multi-robot systems. The improved artificial potential field based on simulated annealing algorithm satisfactorily overcomes the drawbacks of traditional artificial potential field method,so that robots can find a local collision-free path in the complex environment. According to the movement vector trail of robots,collisions between robots can be detected,thereby the collision avoidance rules can be obtained. Coordination between robots by the priority based rules improves the real-time property of multi-robot system. The combination of these two methods can help a robot to find a collision-free path from a starting point to the goal quickly in an environment with many obstacles. The feasibility of the proposed method is validated in the VC-based simulated environment.
文摘Contrary to the conventional wisdom which suggests that a perfectly rational subject with risk-averse attitude should never gamble, this paper provides a vivid example in our real economy for people to expect a positive return to gamble Within the existing literature, scholars have proposed different reasons to explain why an original risk-averse person would start to gamble, with the implicit assumption that the expected payoff of a bet is always lower than its cost. In contrast, our paper discusses when and why a risk-averse person could bet strategically with a positive expected return; in particular, we used field data in Hong Kong to illustrate a vivid scenario for positive expected return in gambling.
文摘The article assesses the determinants of farmers' decisions to participate in organic farming, eliciting farmers risk preferences and empirically analysing farmer's sources of risk and risk management strategies. The ordered probit results indicate that older farmers, who are less risk averse and reside in the sub-ward Ogagwini, Ezigani and Hwayi were more likely to be certified organic. Similarly, the propensity to adopt organic farming is positively correlated to household size, livestock ownership, asset base and tenure security. At higher pay-offs, farmers were intermediate to moderately risk-averse, with little variation according to personal characteristics. In general, price, production and financial risks were perceived as important sources of risk. Seven principal components, explaining 66.13% of the variation were extracted. Socio-economic factors having a significant effect on the various sources of risk were age, gender, education, location, information access and risk taking ability. The dimensions of risk strategies were named as diversification, precautionary savings and social networks. Results provide practical insights for policy changes relevant in motivating the adoption of organic practices, increasing smallholder farmers' capacity to manage risk and driving growth in the organic food market.
文摘Employee stock options (ESOs) have become an integral component of compensation in the US. In view of their significant cost to firms, the Financial Accounting Standards Board (FASB) has mandated expensing ESOs since 2004. The main difficulty of ESO valuation lies in the uncertain timing of exercises, and a number of contractual restrictions of ESOs further complicate the problem. We present a valuation framework that captures the main characteristics of ESOs. Specifically, we incorporate the holder's risk aversion, and hedging strategies that include both dynamic trading of a correlated asset and static positions in market-traded options. Their combined effect on ESO exercises and costs are evaluated along with common features like vesting periods, job termination risk and multiple exercises. This leads to the study of a joint stochastic control and optimal stopping problem. We find that ESO values are much less than the corresponding Black-Scholes prices due to early exercises, which arise from risk aversion and job termination risk; whereas static hedges induce holders to delay exercises and increase ESO costs.
文摘The social security fund investment operations of the social security system of a country or even the whole economy has a very important role in recent years, although China's social security fund management has made great progress, but China's social security fund investment operations in increasing the value of the pursuit of this goal, while also facing tremendous pressure. After years of practice of reform, China's old-age, unemployment and medical insurance and minimum living focused on the social security system has taken shape, but also the corresponding social security fund was established. Part of the problems of social security funds and other investment operations are increasingly apparent. How to achieve the social security fund is necessary to ensure payment, but also realize the accumulation, it is necessary to increase the value, but also to avoid risks, it has become an urgent task of China's reform and development. Social Security Fund Investment Management became the central task of the Social Security System.
基金This research was supported by the Social Science Foundation of the Ministry of Education of China under Grant No. 07JA630015, the National Natural Science Foundation of China under Grant Nos. 70901059 and 70901029, and the Fundamental Research Funds for the Central Universities under Grant No. 105-275171.
文摘This paper investigates a risk-averse inventory model by balancing the expected profit and conditional value-at-risk (CVaR) in a newsvendor model setting. We find out that: i) The optimal order quantity is increasing in the shortage cost for both the CVaR only criterion and the tradeoff objective, ii) For the case of zero shortage cost, the optimal order quantity to the CVaR criterion or tradeoff objective is increasing in the selling price, respectively. However, it may not be monotonic in the selling price when incorporating a substantial shortage cost. Moreover, it may be larger or less than the risk-neutral solution, iii) Under the tradeoff objective function, although the optimal order quantity for the model without shortage cost is increasing in the weight put on the expected profit, this property may not be true in general for the model with a substantial shortage cost. Some numerical examples are conducted to verify our results and observations.
文摘This paper develops a kind of generalized double-sided moral hazard model of contract choice with Cobb-Douglas technology in a frame of principal-agent theory. The two parties, the principal and the agent, generally have different levels of production efficiency, relative importance factor and are risk-averse or risk-neutral. Using this model, we formally prove that the optimal contract maximizes the output net of the disutility of both the parties and carry out some simulations exercise under two special cases which help explain the double-sided moral hazard issues. By focusing on production efficiency, relative importance factor and risk attitude respectively, this paper analyzes the properties of optimal contracts under three cases.
基金supported by the National Natural Science Foundation of China(81271863,81361120405)the Key Research Program of the Chinese Academy of Sciences(KJZD-EW-L01)
文摘Both eukaryotic and prokaryotic pathogens infect the host stably via an immune evasion mecha- nism termed mutually exclusive expression. Nowadays, little is known about this epigenetic mechanism, largely limiting the understanding of pathogenesis of many bacterial, fungal and protozoan pathogens and therefore the development of novel drugs and vaccines. In the most severe malaria parasite, Plasrnodiurn falciparum, there is a major virulence gene family termed vat, by which the variant antigen PfEMP1 is encoded and expressed on the surface of parasite-infected erythrocytes. Each parasite carries about 60 anti- genically various vat genes, however, only one of which is expressed at a given time during infection. P. falciparum expresses PfEMP1s in this clonally variant manner to bind to different human endothelial re- ceptors, allowing the infected erythrocytes to sequester in tissues to escape the host's immune response in- cluding spleen killing and humoral immunity. At present, the mechanism of mutually exclusive expression of the var gene family remains largely unknown, even though there is increasing evidence suggesting im- portant roles of the epigenetic regulation involved in vat gene expression. In addition, epigenetic factors were also found in association with transcriptional regulation of other antigenic variant gene families in P. falciparum. In this paper, we review the current understanding of epigenetic regulations of P. falcipa- rum virulence genes with particular views toward the design of novel vaccines, drugs, and diagnosis to ma- laria.
基金supported by the National Basic Research Program of China (Grant No. 2013CB035501)
文摘Obstacle avoidance is quite an important issue in the field of legged robotic applications, such as rescuing and detecting in complicated environment. Most related researchers focused on the legged robot’s gait generation after ssuming that obstacles have been detected and the walking path has been given. In this paper we propose and validate a novel obstacle avoidance framework for a six-legged walking robot Hexapod-III in unknown environment. Throughout the paper we highlight three themes: (1) The terrain map modeling and the obstacle detection; (2) the obstacle avoidance path planning method; (3) motion planning for the legged robot. Concretely, a novel geometric feature grid map (GFGM) is proposed to describe the terrain. Based on the GFGM, the obstacle detection algorithm is presented. Then the concepts of virtual obstacles and safe conversion pose are introduced. Virtual obstacles restrict the robot to walk on the detection terrain. A safe path based on Bezier curves, passing through safe conversion poses, is obtained by minimizing a penalty function taking into account the path length subjected to obstacle avoidance. Thirdly, motion planning for the legged robot to walk along the generated path is discussed in detail. At last, we apply the proposed framework to the Hexapod-III robot. The experimental result shows that our methodology allows the robot to walk safely without encountering with any obstacles in unknown environment.