Moment equations of a stochastic system with generalized Poisson parameters†

Differential equations for the moments of a system with generalized Poisson parameters are derived by finding the rate of change of the expected value of an arbitrary function of the state variables. Results are very similar to the equations for the moments of tin Ito stochastic differential equation.     

Stability analysis of a feedback system containing periodically varying parameters†

Stability analysis for a third-order feedback system with a periodically varying parameter is presented using a matrix method and approximating the time-varying parameter as piecewise constant over its period. The stability boundaries of such a system are predicted and compared with the boundaries determined by analogue computer simulation. Incidentally a method of generating similar matrices is brought out during this investigation.     

Performance analysis of an inventory–production system with shipment consolidation in the production facility

We consider an inventory–production system consisting of a warehouse and a production facility. The warehouse is used to store products to satisfy customer demands, and its inventory is controlled by an (r,Q)$(r,Q)$ policy. Products ordered by the warehouse are processed in the production facility on a one-by-one basis, and finished products are consolidated into batches to be shipped from the production facility to the warehouse. Using the matrix-analytic methods, explicit solutions are obtained and computational methods are developed for analyzing system performance measures.     

Development of a novel system to quantify the spatial–temporal parameters for crutch-assisted quadrupedal gait

Abstract

Patients with gait disorders often use bilateral crutches along with their own two legs. It is a kind of quadrupedalism. Crutch-assisted gait is usually described and evaluated qualitatively. In this study, we developed a system to quantify the spatial and temporal parameters for crutch-assisted quadrupedalism. Our system consists of walkway hardware and our originally developed software. We specifically extended the measurable area to 1200 mm × 4800 mm, large enough to measure crutch gait. Using our system, we could describe crutch gait precisely. Our system has a capability to evaluate differences between patients and changes within a patient.     

More on the phase-plane analysis of a relay control system†

The transcendental equation relating the parameters of a closed trajectory of a relay system containing a symmetrical two-position element, a dead element and a rational part of the second order has two solutions. It will be shown that only one of these solutions supplies the self-oscillation of the system.

The phase-plane method is developed for systems containing a relay element with hysteresis. The effect of varying any parameter of the system on the period and amplitude of the self-oscillation can be predicted from the transcendental equation.     

Global qualitative analysis of a predator–prey system with Allee effect on the prey species

In this paper, the Allee effect is incorporated into a predator–prey model with linear functional response. Compared with the predator–prey model without the Allee effect, it is found that the Allee effect of the prey species increases the extinction risk of both the prey and predator. If the Allee effect of the prey species is strong and the mortality of the predator species is relatively low, then the prey and predator cannot coexist after the predator invasion. Moreover, it is shown that the model with Allee effect undergoes the heteroclinic loop bifurcation and subcritical and supercritical Hopf bifurcations. With the brokenness of the heteroclinic loop, a stable or unstable limit cycle will appear. The Allee effect of the prey species can lead to unstable or stable periodic fluctuations. It is also found that the positive equilibrium of the model could change from stable to unstable, and then disappear when the strength of Allee effect increases continuously from zero.     

Performance analysis and simulation of TH-PPM UWB system in image transmission

TH-PPM-UWB system of image transmission is presented in this paper. And then the performance analysis over an ideal AWGN （Additive White Gaussian Noise） channel is given. The studies indicate that the selection of parameters has a great influence on BER （Bit Error Rate） of the system, especially the number of pulses per information bit. The simulation results of image transmission demonstrate that a larger number of pulses per information bit will lead to better BER performance.     

Computing the regularization of a linear differential–algebraic system

We study the regularization problem for linear differential–algebraic systems. As an improvement of former results we show that any system can be regularized by a combination of state-space and input-space transformations, behavioral equivalence transformations and a reorganization of variables. The additional state feedback which is needed in earlier publications is shown to be superfluous. We provide an algorithmic procedure for the construction of the regularization and discuss computational aspects.     

Precise and full extraction of the coupling-of-mode parameters with periodic Green''''s function

Due to the more and more stringent requirements on surface acoustic wave (SAW) filters performances, recently considerable attention has been focused on the investigation of low-loss SAW filters in the last decade. Most low-loss filters, such as single phase unidirectional transducers (SPUDT), employ the electrodes multi-reflection effects to realize low insertion loss. In the design of low-loss filters, the phenomenological coupling-of-mode (COM) model[1] method is frequently used. Its …     

Overall availability and risk analysis of a general robot–safety device system

We analyse the availability of a general robot–safety device system characterised by the feature of cold standby and by an admissible risky state. In contrast to the previous literature, we allow a general failure-free time distribution for the robot and, as an example, we present computational results for Coxian failure and repair time distributions. In order to decide whether the risky state is admissible, we introduce a risk criterion based on the notion of rare events. The criterion is always satisfied in the case of fast repair.     

Approximate analysis of a queueing–inventory system with early and delayed server vacations

We propose a model for a servicing system with perishable inventory and a finite queue of impatient claims where the server can be in one of three states: operational, early and delaying vacations. We develop a method for approximate computation of the system’s characteristics. We show results of numerical experiments.     

Time-series analysis of NDVI from AVHRR data over the Hindu Kush–Himalayan region for the period 1982–2006

The Hindu Kush–Himalayan (HKH) region with its surrounding mountains in central Asia is a region that has been warming at an alarming rate and is sensitive to climate change due to its heterogeneous terrain and high altitude. In a region where research is limited due to the paucity of field-based biophysical observations, analysis of remotely sensed data such as the normalized difference vegetation index (NDVI) can provide invaluable information on spatio-temporal patterns in linkages among land use, climate and vegetative phenological cycles, and trends in vegetative cover. In this study, NDVI data with 8 km spatial resolution for each 15 day composite period from 1982 to 2006 were analysed using a seasonal trend analysis technique, where the first step determines the annual mean and seasonal NDVI patterns across the HKH region. The second step analyses the non-parametric trends in magnitude and timing of the annual mean and seasonal NDVI cycle. The seasonal vegetation cycles were compared for the first and last ten years of the time series and were also analysed across areas undergoing significant change. Results indicated an overall greening trend in NDVI magnitude in most areas, particularly over open shrubland, grassland and cropland. Trends in the annual seasonal timing of NDVI indicated an earlier green-up for most parts of this region. Results also confirmed deforestation trends observed in a few states in northeastern India and Myanmar (Shan state) within the HKH region.