On stabilization by state feedback for neutral differential difference equations

In this paper we consider a class of feedback operators for a linear differential difference equation of the neutral type. We show that if a system has unstable neutral root chains, any stabilizing feedback operator in this class must contain a derivative of the delayed state component. Under the assumption of exact controllability, we construct a stabilizing feedback operator.     

Design of a Planar Ultrawideband Antenna With a New Band-Notch Structure

A novel planar ultrawideband (UWB) antenna with band-notched function. The antenna consists of a radiation patch that has an arc-shaped edge and a partially modified ground plane. The antenna that makes it different from the traditional monopole antenna is the modification in the shape of ground plane, including two bevel slots on the upper edge and two semicircle slots on the bottom edge of the ground plane. These slots improve the input impedance bandwidth and the high frequency radiation performance. With this design, the return loss is lower than 10 dB in 3.1-10.6 GHz frequency range and the radiation pattern is highly similar to the monopole antenna. By embedding a pair of T-shaped stubs inside an elliptical slot cut in the radiation patch, a notch around 5.5 GHz WLAN band is obtained. The average gain is lower than -18 dBi in the stopband, while the patterns and the gains at frequencies other than in the stopband are similar to that of the antenna without the band-notched function.     

An industry-level knowledge management model—a study of information-related industry in Taiwan

Most knowledge management (KM) literature investigates related issues from the perspectives of organizational and national layer. While observing KM practices, especially in less developed countries (LDCs), many KM activities are happened in industrial layer. Hence, the primary purpose of this study is to explore the content of industry-layer knowledge management (i.e., ILKM) and how ILKM activities are practiced. This study, first, classifies ILKM as four modes, named knowledge clustering, knowledge enlarging, knowledge exchanging, and knowledge initiating. Following KM-related literature and practices, this study constructs the ILKM model, and defines and lists content and activities of the four ILKM modes, by which a four sub-construct, 20-item ILKM scale is constructed. A 123-respondents empirical survey, selecting Taiwan's information equipment industry as the sample, confirms the reliability and validity of ILKM scale. This study also provides suggestions and directions toward ILKM practices and researches for the future.     

Exploring the implementation and application of Bluetooth technology in the shipping industry

Bluetooth technology has become more and more popular in today's worldwide operations. Its impact on the shipping industry is specifically unique and profound. The purpose of this study is to explore the implementation and application of Bluetooth technology in the shipping industry. This article first introduces the standard and technology of Bluetooth as well as the efforts to develop and promote the standard. Then, the current status of Bluetooth applications in the shipping industry is discussed. Further, three cases, including FedEx, UPS and DHL, are studied along with a Strategic-Managerial-Organizational-Technological-Security-Social (SMOTSS) analysis. The article is concluded with the implications and future of Bluetooth technology.     

Path-based approach to integrated planning and control for robotic systems: A path-based approach provides an analytical integration of robot planning and control. As a result, the task level control can be achieved, and the system is capable of coping with unexpected or uncertain events

Our newly developed event-based planning and control theory is applied to robotic systems. It Introduces a suitable action or motion reference variable other than time, but directly related to the desired and measurable systems output, called event. Here the event is the length of the path tracked by a robot. It enables the construction of an integrated planning and control system where planning becomes a real-time closed-loop process. The path-based integration planning and control scheme is exemplified by a single-arm tracking problem. Time and energy optimal motion plans combined with nonlinear feedback control are derived in closed form. To the best of our knowledge, this closed-form solution was not obtained before. The equivalence of path-based and time-based representations of nonlinear feedback control is shown, and an overall system stability criterion has also been obtained. The application of event-based integrated planning and control provides the robotic systems the capability to cope with unexpected and uncertain events in real time, without the need for replanning. The theoretical results are illustrated and verified by experiments.     

Feedback control of robot Arm with discrete nonlinear model

This article looks at the problem of controlling a robot arm from a discrete time perspective. We develop the theories and obtain results that feedback linearizes the discrete nonlinear system representing a PUMA 560 robot arm. The effect of sampling on the performance of the arm has been studied and shown through experiments. The results presented here, where the nonlinear robot model has been linearized and controlled completely in discrete time, are new to the robotics literature. We shown certain restrictions necessary on the sampling time of the system. The results obtained have been experimentally verified at the Center for Robotics and Automation at Washington University. Because a number of researchers have addressed the problem of loss of feedback linearizability under sampling, it was important to develop theories and obtain results in discrete time that take into consideration the effects due to sampling. This problem has been addressed here. Analysis of the control law under the assumptions of bounded input is performed and a recursive sensitivity function is derived. The results we obtain in discrete time show the dependency of the performance of the arm on the sampling time. It has been seen that with a higher sampling frequency the performance of the arm substantially improves and it is expected that close to 1000 Hz sampling rate, the peak performance of the PUMA 560 robot arm, will be reached.     

Temperature Dependence of Output Voltage Generated by Interaction of Threshold Voltage and Mobility of an NMOS Transistor

Mutual compensation of mobility andthreshold voltage temperature variations mayresult in a zero temperature coefficient (ZTC)bias point of an NMOS transistor. Theconditions under which this effect occurs,stability of this bias point, and thetemperature dependence of the output voltagefor a diode-connected transistor operating inthe vicinity of ZTC point are investigated inthis paper. Some possible applications of thiseffect include temperature sensors with lineardependence of voltage versus temperature, andvoltage and current reference circuits. Thetheory is verified experimentallyinvestigating the temperature behavior of anNMOS transistor realized in 0.35 m CMOSprocess. The design and simulation results ofsimple current and voltage reference circuitsfor implementation in 0.18 m CMOStechnology are given.     

Infrared extinction of the powder of brass 70Cu/30Zn calculated bythe FDTD and turning bands methods [military smoke screeningapplications]

The finite-difference time-domain (FDTD) method is used to calculate the specific extinction cross section of the powder of brass 70Cu/30Zn with 10³ to 2.16-10⁵ cubical particles for cell sizes in the range of 0.025 to 0.5 μm at infrared frequency. The digitized models with a random process using the turning bands method are simulated for the powder of brass 70Cu/30Zn. From theoretical calculations, the value of the specific extinction cross section of the powder of brass 70Cu/30Zn is between 0.1 to 4.6 m²/g. While from the experimental measurement, the value of the specific extinction cross section is between 0.58 to 3.78 m²/g. Most of the theoretical results make a good agreement with those obtained from the experimental measurements for the cell sizes of particles in the range of 0.925 to 0.5 μm. From the numerical calculations, it is also found that there is a resonant extinction value occuring at the resonant particle size d₀ which is approximately 2.54-n_p ^-0.293 μm determined by a least square curve fitting method, where n_p is the number of particles. The resonant value calculated by the numerical solution is larger than the maximum value obtained from the experimental measurement. The work has applications to military smoke screening