Workpiece localization, with novel applications such as workpiece setup, refixturing and dimensional inspections, is a problem of permanent importance in manufacturing. Using the popular least square formulation, seve...
详细信息
Workpiece localization, with novel applications such as workpiece setup, refixturing and dimensional inspections, is a problem of permanent importance in manufacturing. Using the popular least square formulation, several geometric algorithms have been developed for workpiece localization over the last few years. In this paper, we analyze and compare the performance of three localization algorithms based on the following criteria: (a) robustness with respect to variations in initial conditions; (b) accuracy of computed results; and (c) computational efficiency. We develop an approach for improving the robustness of the algorithms for workpieces with sculptured surfaces for which the region of convergence is typically small. Based on simulation results, we also discuss sensitivity of the algorithms with respect to the number of measurement points and give a lower bound on this number for recovering a Euclidean transformation with certain accuracy.
This paper describes an operating principle and features of a newly-developed parallel resonant DC link circuit with an active voltage clamped PWM control scheme. In particular, a new conceptual design procedure of th...
详细信息
This paper describes an operating principle and features of a newly-developed parallel resonant DC link circuit with an active voltage clamped PWM control scheme. In particular, a new conceptual design procedure of the resonant DC link treated here is illustrated and discussed including a practical design example under zero voltage and zero current soft switching. In this paper, a bidirectional power flow three-phase voltage-fed PWM power converter using a resonant DC link which is applied to a utility-interfaced battery energy storage system is analyzed for load leveling, battery charging, reactive current compensation and active filtering schemes. Finally, the system performances of this converter mode or inverter mode and the effectiveness of this resonant DC link circuit topology and resonant DC link power processor are demonstrated on the basis of simulation results.
In this paper we compare, by simulation based on real traffic traces, the EFCI (explicit forward congestion indication) and the ERF (explicit rate feedback) rate-based flow control algorithms for the available bit rat...
详细信息
In this paper we compare, by simulation based on real traffic traces, the EFCI (explicit forward congestion indication) and the ERF (explicit rate feedback) rate-based flow control algorithms for the available bit rate (ABR) service in ATM networks. The factors under consideration are: (1) distance from source to destination and (2) rate of resource management (RM) cells. Although no significant fairness throughput problem has been identified in both EFCI and ERF, sources with high end-to-end propagation delay will experience higher queueing delay and loss probability. In this paper, we have also shown that although EFCI can lead to considerably lower utilisation than ERF if the parameters are set arbitrarily, it can perform as good as or close to ERF if there were complementary software which can compute the optimal parameters for EFCI based on the on-line measurement of traffic streams.
Optical code division multiple access has been proposed as an alternative multiple access scheme for multiuser fiber-optic communication systems. Many previous works on the receivers for such systems have focused on t...
详细信息
Optical code division multiple access has been proposed as an alternative multiple access scheme for multiuser fiber-optic communication systems. Many previous works on the receivers for such systems have focused on the correlation receiver which is optimal in the single user case. However, it has been shown that the performance of the correlation receiver is unsatisfactory when there is a large number of interferers. Multiuser detection becomes an appealing method to improve the system performance. In this paper, a new multiuser detector for optical code division multiple access communication systems, referred to as the multistage decorrelating receiver, is proposed. Its structure is much simpler than the optimal multiuser detector at the expense of slight performance degradation. Both simulation and analysis of the receiver are carried out. Comparison of the proposed detector with several other receivers is also presented.
Most of the tools that are used in performing manipulation tasks in laparoscopic surgery are graspers and needle drivers. Although the operation of such basic tools is rather simple, their combination with remote acce...
详细信息
Most of the tools that are used in performing manipulation tasks in laparoscopic surgery are graspers and needle drivers. Although the operation of such basic tools is rather simple, their combination with remote access to the surgical site and an indirect field of view makes the usage of such mechanisms challenging. This means that surgeons have to undergo a series of training sessions in order to gain proper hand/eye coordination. In addition, due to the structure of these mechanisms, the sense of touch has been reduced to a minimum. One challenge of research and development has been to design a force-reflective grasper that can reflect the sense of touch back into the handle. In addition, considerable efforts are being focused on developing a virtual laparoscopic trainer where the sense of touch in manipulating virtual tissues and organs can be reflected back to the hand of the surgeon through the proper design of haptic interfaces. This paper presents force propagation models which can be used in the modelling, design and interpretation of the force sensing system and reflecting devices. The proposed models agree with the experimental observation previously published in the literature for describing the relationships between the magnitude of the grasping force and the applied force at the handle.
We study routing methods in all-optical switching networks. In all-optical switching networks, the connection with more hops encounters more call blocking, and it is especially true in optical networks with no wavelen...
详细信息
We study routing methods in all-optical switching networks. In all-optical switching networks, the connection with more hops encounters more call blocking, and it is especially true in optical networks with no wavelength conversions. We therefore consider an alternate routing method with limited trunk reservation in which connections with more hops are prepared more alternate routes. Through developing an approximate analytic approach, we show that our method keeps good performance when compared with the existing alternate routing methods, and also that the fairness among connections can be improved. Further performance improvement is investigated by introducing a wavelength assignment policy and a dynamic routing method. An effectiveness of the proposed method is investigated through simulation.
We developed a new hierarchical modular approach for synthesis of area-minimal core-based data-intensive systems. The optimization approach employs a novel global least-constraining most-constrained heuristic to minim...
详细信息
ISBN:
(纸本)9780818682001
We developed a new hierarchical modular approach for synthesis of area-minimal core-based data-intensive systems. The optimization approach employs a novel global least-constraining most-constrained heuristic to minimize the instruction cache misses for a given application, instruction cache size and organization. Based on this performance optimization technique, we constructed a strategy to search for a minimal-area processor core, and an instruction and data cache which satisfy the performance characteristics of a set of target applications. The synthesis platform integrates the existing modeling, profiling, and simulation tools with the developed system-level synthesis tools. The effectiveness of the approach is demonstrated on a variety of modern real-life multimedia and communication applications.
This paper presents a salient method to find an optimal bandwidth for low noise phase-locked loop (PLL) applications by analyzing a discrete-time model of charge-pump PLLs based on ring oscillator VCOs. The analysis s...
详细信息
ISBN:
(纸本)0780336623
This paper presents a salient method to find an optimal bandwidth for low noise phase-locked loop (PLL) applications by analyzing a discrete-time model of charge-pump PLLs based on ring oscillator VCOs. The analysis shows that the timing jitter of the PLL system depends on the jitter in the ring oscillator and an accumulation factor which is inversely proportional to the bandwidth of the PLL. Further analysis shows that the timing jitter of the PLL system, however, proportionally depends on the bandwidth of tile PLL when an external jitter source is applied. The analysis of the PLL timing jitter of both cases gives the clue to the optimal bandwidth design for low noise PLL applications. simulation results using a C-language PLL model are compared with the theoretical predictions and show good agreement.
We describe a centralized approach to testing that distributed fault-tolerant protocols satisfy their safety and timeliness specifications in the presence of the very failures they are designed to tolerate. CESIUM is ...
详细信息
We describe a centralized approach to testing that distributed fault-tolerant protocols satisfy their safety and timeliness specifications in the presence of the very failures they are designed to tolerate. CESIUM is a testing environment based on the centralized simulation of distributed executions and failures. Processes are run in a single address space while providing the appearance of a truly distributed execution. The human tester can force the occurrence of arbitrary failures and security attacks. The implementations under test are not instrumented for testing purposes, and their source codes need not be available. We prove that CESIUM can execute exactly the set of runs feasible in the real distributed system being simulated. We also show that there are safety and timeliness properties in the specifications of many existing distributed protocols that cannot be tested in practical distributed systems. All of these properties can, however, be accurately tested by CESIUM without introducing any perturbation in test experiments.
A nonvolatile memory called FeRAM (Ferroelectronic Random Access Memory) is one of the promising memory devices. This paper presents a dual plane FeRAM (DFeRAM) architecture for recovery in the shared disk parallel da...
详细信息
A nonvolatile memory called FeRAM (Ferroelectronic Random Access Memory) is one of the promising memory devices. This paper presents a dual plane FeRAM (DFeRAM) architecture for recovery in the shared disk parallel database system. This paper also presents a recovery algorithm based on a shadow paging method using a DFeRAM architecture. We compare the performance of the log based method and that of our method based on simulation results, which show that our method is better than the log based method when both methods use a nonvolatile memory.
暂无评论