An adaptive antenna impedance matching system for mobile communication terminals is proposed. The system adaptively controls two varactors of the pi-network matching circuit detecting the change in the refection coeff...
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An adaptive antenna impedance matching system for mobile communication terminals is proposed. The system adaptively controls two varactors of the pi-network matching circuit detecting the change in the refection coefficient between the antenna combined with the matching circuit and the RF front end of a transceiver. This system consists mainly of analog circuits and employs only a simple algorithm for convergence, therefore does not need any complicated mathematical formulation for modeling of the system itself as well as its nonlinear control elements. Also the proposed system utilizes only simple digital circuits for timing generation. In this paper, the performance of the adaptive impedance matching system is investigated by simulation. The input impedance of the antenna is alternated assuming the change of the environment due to a human head or a hand, and etc. In addition, a better performance is obtained in terms of the input power to the antenna by holding the adaptive control when the reflection is smaller than a certain threshold value. As a result, it is found that the input power to the antenna for transmission can be increased by about 2dB per second compared with a fixed capacitance matching system.
An adaptive antenna impedance matching system for mobile communication terminals is proposed. The system adaptively controls two varactors of the pi-network matching circuit detecting the change in the refection coeff...
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An adaptive antenna impedance matching system for mobile communication terminals is proposed. The system adaptively controls two varactors of the pi-network matching circuit detecting the change in the refection coefficient between the antenna combined with the matching circuit and the RF front end of a transceiver. This system consists mainly of analog circuits and employs only a simple algorithm for convergence, therefore does not need any complicated mathematical formulation for modeling of the system itself as well as its nonlinear control elements. Also the proposed system utilizes only simple digital circuits for timing generation. The performance of the adaptive impedance matching system is investigated by simulation. The input impedance of the antenna is alternated assuming the change of the environment due to a human head or a hand, and etc. In addition, a better performance is obtained in terms of the input power to the antenna by holding the adaptive control when the reflection is smaller than a certain threshold value. As a result, it is found that the input power to the antenna for transmission can be increased by about 2dB per second compared with a fixed capacitance matching system.
In today's challenging environment, companies gain a competitive advantage by reducing time-to-market of their products. This effort requires an integration of various technologies and effective utilization of sim...
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In today's challenging environment, companies gain a competitive advantage by reducing time-to-market of their products. This effort requires an integration of various technologies and effective utilization of simulation tools. As an integral part of any manufacturing environment, operator health and safety is a primary focus of the companies. digitalhumanmodeling and virtual reality tools provide an excellent solution to factor human element early in the design phase and to make proactive choices in workplace and equipment design decisions. In this paper, the process of ergonomics analysis within digital environment is discussed, and an application is summarized. The case study gives details of the integration of digitalhumanmodeling, motion capturing, and ergonomics analysis in an automobile part sub-assembly process.
human models are viable methods of introducing human factors and ergonomic objectives into the design process at an early stage. Used correctly, they allow users to simulate and analyze potential human-machine interac...
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modeling and simulation have become integral parts of the engineering process and will assume an even greater role in the years ahead. DoD initiatives like Simulation-Based Acquisition mandate a central role of simula...
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ne object-oriented modeling of interactive multimedia applications in the OMMMA approach is designed to enable multimedia software developers to create comprehensive analysis and design models of multimedia software. ...
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ISBN:
(纸本)0780382250
ne object-oriented modeling of interactive multimedia applications in the OMMMA approach is designed to enable multimedia software developers to create comprehensive analysis and design models of multimedia software. For development of highly usable multimedia applications, this approach must be embedded in a more holistic development process that takes a user-oriented perspective on multimedia software development. In this paper, we elaborate on the differences between user-centred design activities and object-oriented software design activities and outline their integration in a comprehensive development process.
digital clay represents a new type of 3-D human-computer interface device that enables tactile and haptic interactions. The digital clay surface is computer controlled and can be commanded to acquire a wide variety of...
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digital clay represents a new type of 3-D human-computer interface device that enables tactile and haptic interactions. The digital clay surface is computer controlled and can be commanded to acquire a wide variety of desired shapes, or be deformed by the user in a manner similar to that of real clay. In this paper, we present the ideas underlying digital clay and an example design of a digital clay device meant for general-purpose modeling. We also introduce the concept of low degree-of-freedom digital clay devices, in which the clay surface can acquire a limited range of shapes, for example, to describe the shapes of automotive front-ends. Each degree of freedom moves a region of the clay surface through a range of predefined shapes. We investigate geometric modeling techniques for defining the ranges of shapes and relate the shapes to forward and inverse kinematics of the deformable structures that control surface shape. To illustrate the application of the digital clay concept, an example low degree-of-freedom clay device for modeling automotive front ends is presented and discussed.
We propose a new electronic design to overcome design limitations in PET that arise from the need to use high-cost fast analog-to-digital converters (ADCs). Our design may completely remove the use of ADCs in PET, and...
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We propose a new electronic design to overcome design limitations in PET that arise from the need to use high-cost fast analog-to-digital converters (ADCs). Our design may completely remove the use of ADCs in PET, and possibly the constant fraction discriminator (CFD) as well. In our approach, we model the eletric pulse generated upon an event detection by a fast linearly rising edge followed by a slower exponential decay. Based on this modeling, basic properties of the pulse that are relevant for PET event detection, including the decay constant, the peak value and the peak time, can be determined from simple time interval measurements of the pulse. In this work, we will present methods for determining these pulse properties and propose eletronic implementations of these methods. We will employ computer simulations to conduct sensitivity analysis of the proposed new event processing methods to modeling errors, noise and clock rate.
This paper describes the study performed to build an accurate and reliable digital model of a human hand. A mould was manufactured using alginate contact-safe rubber and a plaster model made. The model was digitized u...
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The purpose of this study is to develop an evaluation method for the postural stability using a digitalhuman model. Experiments were carried out to measure two kinds of stability limits defined in this study. Based o...
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