3,289 research outputs found

    Microcomputer Aided Selection Of Robot Manipulators

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    This paper presents two programs for microcomputer aided assessment of the performance of robot manipulators. The first program automatically generates robot models based on user-supplied kinematic parameters. The program also derives a kinematic model that relates the motion of manipulator end-effector to the motion of the joints using the inverse kinematic approach. The approach uses a robust inversion technique that can handle singular conditions as well as joint redundancy. A user can optionally select evaluation of kinematic capabilities of the robot manipulator, such as the ability of the end-effector to reach a specified position and orientation in space or the evaluation of the work space. The second program generates dynamic variables, such as forces and torques, based on user-supplied dynamic parameters and equations of motion of the various joints. Both programs are written for implementation on personal computers. Several runs were carried out to demonstrate the capability and execution times of the two program

    Cannabinoid receptor 1 signaling in cardiovascular regulating nuclei in the brainstem: A review

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    Cannabinoids elicit complex hemodynamic responses in experimental animals that involve both peripheral and central sites. Centrally administered cannabinoids have been shown to predominantly cause pressor response. However, very little is known about the mechanism of the cannabinoid receptor 1 (CB1R)-centrally evoked pressor response. In this review, we provided an overview of the contemporary knowledge regarding the cannabinoids centrally elicited cardiovascular responses and the possible underlying signaling mechanisms. The current review focuses on the rostral ventrolateral medulla (RVLM) as the primary brainstem nucleus implicated in CB1R-evoked pressor response

    The city network paradigm: new frontiers;

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    This chapter provides a survey of recent developments of positive as well as normative theories of city systems. Static theory of city system emphasizes the factors that result in the formation of cities through the interaction between two opposing forces: i) agglomeration economy; ii) agglomeration diseconomy. Furthermore, the theory examines the interaction between cities within the national economy through intercity trade and migration, which shape the internal population composition and industrial structure of cities within the system. New development of this theory has been influenced by industrial organization and economic growth together with the new urban economic paradigm. This chapter focuses on the following questions: What are the factors that lead to the formation of cities? When do cities specialize in production and when do they diversify? When do both specialized cities and diversified cities coexist? What determines the number and sizes of cities of different types in an economy? What are the factors that determine skill distribution and income disparities among different types of cities? What are the impacts of income inequalities on welfare? What are the tax and or subsidy scheme that would result in a Pareto-efficient allocation of resources in a system of cities? Do we need the intervention of federal government in order to achieve a Pareto-efficient allocation of resources in a system of cities? These questions are addressed in a spatial general equilibrium model of a closed economy consisting of a system of monocentric cities

    Trade, Urban Systems, and Labor Markets

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    This paper investigates the impacts of free trade on the structure of urban systems, skill distribution, and income disparities. The paper proposes a model that integrates international trade theory and the theory of urban system. This is done in a two sector, spatial general equilibrium model of a North-South trade. Each country is populated with a continuum of unskilled workers with heterogeneous potential ability. Through differential training costs, workers with different potential ability can achieve the same productivity. Workers can acquire a skill by investing in training. Thus, skill distribution in both countries is determined endogenously in the model through self-selection. The economy produces a final good with the use of a high-tech intermediate input and unskilled workers. Horizontally differentiated skilled workers produce the high-tech intermediate input. Cities are formed in this model as a result of investment in setup cost, i.e., public infrastructures. I characterize two different types of spatial equilibria: a closed-economy equilibrium, in which each country consists of a system of cities without trade, and a free-trade equilibrium, in which we allow for trade between cities and countries

    The city network paradigm: new frontiers;

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    This chapter provides a survey of recent developments of positive as well as normative theories of city systems. Static theory of city system emphasizes the factors that result in the formation of cities through the interaction between two opposing forces: i) agglomeration economy; ii) agglomeration diseconomy. Furthermore, the theory examines the interaction between cities within the national economy through intercity trade and migration, which shape the internal population composition and industrial structure of cities within the system. New development of this theory has been influenced by industrial organization and economic growth together with the new urban economic paradigm. This chapter focuses on the following questions: What are the factors that lead to the formation of cities? When do cities specialize in production and when do they diversify? When do both specialized cities and diversified cities coexist? What determines the number and sizes of cities of different types in an economy? What are the factors that determine skill distribution and income disparities among different types of cities? What are the impacts of income inequalities on welfare? What are the tax and or subsidy scheme that would result in a Pareto-efficient allocation of resources in a system of cities? Do we need the intervention of federal government in order to achieve a Pareto-efficient allocation of resources in a system of cities? These questions are addressed in a spatial general equilibrium model of a closed economy consisting of a system of monocentric cities

    FOOD CONSUMPTION AND UTILISATION OF THE GRASSHOPPER CHROTOGONUS LUGUBRIS BLANCHARD (ORTHOPTERA, ACRIDOIDEA, PYRGOMORPHIDAE) AND ITS EFFECT ON THE EGG DEPOSITION

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    The grasshopper is found all the year round. It is considered as a pest for seedlings. The consumption index differed significantly between groups fed on different diets. Mated females consume more food than virgin females or virgin males. The highest values were recorded for the bean seedlings fed groups indicating some inadequacy in the nutritional value of bean. The growth rate was the highest in clover fed groups. Insects were able to digest bean and clover more efficiently than either wheat seedlings or cotton leaves. The growth rate was accompanied with a higher C.I. in bean, wheat, and cotton indicating that most of these food was excreted. The ECD and ECI were significantly higher in clover fed groups. This indicated that clover was utilised efficiently than the other groups. The different food stuff affected the egg production which could be attributed to the nutritional efficiencies of these diets. The preovipositional period and number of egg-pods were also affected. The number of abnormal egg-pods was the highest in the bean seedlings fed groups

    Skill Dierentiation and Income Disparity in a Decentralized Matching Model of North-South Trade

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    This paper develops a North-South trade model in which the South produces food and the North produces both food and a high-tech good. Food production is undertaken by unskilled workers while the high-tech product is made only by horizontally dierentiated skilled workers. Due to the possibility of a peer-group effect, we allow the unskilled workers in the North to be equally or more productive than in the South. Horizontal matching of skilled workers is generally imperfect and the skilled wages are determined by a symmetric Nash bargain. We characterize two dierent types of equilibrium: a closed-economy equilibrium without trade and a free trade equilibrium without labor mobility. We then extend the benchmark framework to consider the presence of transport costs. In all cases with trade, the equilibrium properties of goods pricing, the volume of trade and wage disparities are examined.skill heterogeneity and matching, north-south trade, wage inequality

    Assessing silica and dissolved oxygen effects on copper corrosion control in southern Nevada water treatment and supply system

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    A pilot plant study was performed to investigate both the effect of silica on the corrosion process in the water system, and the effect of increased oxygen concentration resulting from ozonation on copper corrosion in the water system. The piping system used in the pilot plant resembled a household piping system, and consisted of four loops of copper pipes. Silica was added to the finished water before entering the loops at three different concentrations and corrosion was monitored by measuring copper concentration in first-draw weekly samples taken from the pilot system. Silica addition was monitored on a daily basis. Alkalinity, pH, dissolved oxygen, temperature, and conductivity were also measured, and the corrosivity of each water was calculated; Statistical and thermodynamic chemical analysis were performed to evaluate the results in chapter, and the most effective dosage of silica was determined. An average of 11.3 mg/l applied silica concentration was found the most effective dosage in retarding the corrosion rate. Increased in dissolved oxygen concentration had insignificant effect on dissolved copper concentration; A multiple linear relationship was found to predict copper concentration in loop 1, where no silica was added, as a function of alkalinity and temperature. It was also found that the formation of Cu(OH){dollar}\sb2,{dollar} Cu(CO{dollar}\sb3),{dollar} CuHCO{dollar}\sb3\sp{+1},{dollar} and Cu(CO{dollar}\sb3)\sb2\sp{-2}{dollar} were thermodynamically favored under the experiment conditions in loop 1

    Skill distribution and income disparity in a north-south trade model;

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    What are the impacts of free trade agreement on the social welfare of different groups of labor force in a developed country? What is the impact of free trade on a developed country 19s income disparity? What is the effect of free trade on the skill distribution of a developed country? The objective of this paper is to address the above questions in a simple two-sector general-equilibrium North-South trade model in which both countries produce one final good and one high-tech intermediate input. Horizontally differentiated skilled workers produce the high-tech intermediate input. The final good is produced with the use of a high-tech intermediate input and unskilled labor. Each country is populated by a continuum of unskilled workers with differential potential ability. Workers in the North and South can acquire skill by investment in training or education. Thus, skill distribution in the North and South is determined endogenously in the model through a self-selection. I characterize two different types of equilibrium: a closed-economy equilibrium without trade and free trade equilibrium. Then, I investigate the impact of free trade, in the presence of training costs, on the skill distribution within each country, income disparity, and social welfare
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