There are several areas in the plywood industry where Operations Research techniques have greatly assisted in better decision-making. These have resulted in improved profits, reduction of wood losses and better utilization of resources. Realizing these, some of the plywood manufacturing firms in the developed countries have established separate Operations Research departments or divisions. In the face of limited raw-material resources, raising costs and a competitive environment, the benefits attributable to the use of these techniques are becoming more and more significant. 相似文献
Since computer networks play an important role in distributed computing environments, an application's performance depends heavily on the quality of service provided by the communication networks. To ensure a high performance, the characteristics of wide area networks, WANs, must be well understood. This paper presents methodologies to characterize WAN traffic based on real measurements from Bellcore's backbone network that connects remote sites using dedicated T1 links. This paper also suggests some workload models that can be used for wide area network sizing and performance evaluation studies. It is found that the inter-site traffic pattern depends on the time of the day and the day of the week. Furthermore, the traffic between two sites is found to be reasonably symmetric, except for those sites designated as back-up sites. The coefficient of variation is used as a measure for the traffic burstiness and it is found to be 1·5 degree during working hours. The methods presented here are easy to use and cost-effective. 相似文献
Type 2 diabetes (T2D) typically occurs in the setting of obesity and insulin resistance, where hyperglycemia is associated with decreased pancreatic β-cell mass and function. Loss of β-cell mass has variably been attributed to β-cell dedifferentiation and/or death. In recent years, it has been proposed that circulating epigenetically modified DNA fragments arising from β cells might be able to report on the potential occurrence of β-cell death in diabetes. Here, we review published literature of DNA-based β-cell death biomarkers that have been evaluated in human cohorts of islet transplantation, type 1 diabetes, and obesity and type 2 diabetes. In addition, we provide new data on the applicability of one of these biomarkers (cell free unmethylated INS DNA) in adult cohorts across a spectrum from obesity to T2D, in which no significant differences were observed, and compare these findings to those previously published in youth cohorts where differences were observed. Our analysis of the literature and our own data suggest that β-cell death may occur in subsets of individuals with obesity and T2D, however a more sensitive method or refined study designs are needed to provide better alignment of sampling with disease progression events. 相似文献
We consider buffer management of unit packets with deadlines for a multi-port device with reconfiguration overhead. The goal
is to maximize the throughput of the device, i.e., the number of packets delivered by their deadline. For a single port or
with free reconfiguration, the problem reduces to the well-known packets scheduling problem, where the celebrated earliest-deadline-first
(EDF) strategy is optimal 1-competitive. However, EDF is not 1-competitive when there is a reconfiguration overhead. We design
an online algorithm that achieves a competitive ratio of 1−o(1) when the ratio between the minimum laxity of the packets and the number of ports tends to infinity. This is one of the
rare cases where one can design an almost 1-competitive algorithm. One ingredient of our analysis, which may be interesting
on its own right, is a perturbation theorem on EDF for the classical packets scheduling problem. Specifically, we show that
a small perturbation in the release and deadline times cannot significantly degrade the optimal throughput. This implies that
EDF is robust in the sense that its throughput is close to the optimum even when the deadlines are not precisely known. 相似文献
Conducting polymer composites of polypyrrole/yttrium oxide (PPy/Y2O3) were synthesized byin situ polymerization of pyrrole with Y2O3 using FeCl3 as an oxidant. The Y2O3 is varied in five different weight percentages of PPy in PPy/Y2O3 composites. The synthesized polymer composites are characterized by infrared and X-ray diffraction techniques. The surface
morphology of the composite is studied by scanning electron microscopy. The glass transition temperature of the polymer and
its composite is discussed by DSC. Electrical conductivity of the compressed pellets depends on the concentration of Y2O3 in PPy. The frequency dependent a.c. conductivity reveals that the Y2O3 concentration in PPy is responsible for the variation of conductivity of the composites. Frequency dependent dielectric constant
at room temperature for different composites are due to interfacial space charge (Maxwell Wagner) polarization leading to
the large value of dielectric constant. Frequency dependent dielectric loss, as well as variation of dielectric loss as a
function of mass percentage of Y2O3 is also presented and discussed. 相似文献
We show that deadlocks due to dependencies on consumption channels are a fundamental problem in wormhole multicast routing. This type of resource deadlocks has not been addressed in many previously proposed wormhole multicast algorithms. We also show that deadlocks on consumption channels can be avoided by using multiple classes of consumption channels and restricting the use of consumption channels by multicast messages. We provide upper bounds for the number of consumption channels required to avoid deadlocks. In addition, we present a new multicast routing algorithm, column-path, which is based on the well-known dimension-order routing used in many multicomputers and multiprocessors. Therefore, this algorithm could be implemented in existing multicomputers with simple changes to the hardware. Using simulations, we compare the performance of the proposed column-path algorithm with the previously proposed Hamiltonian-path-based multipath and an e-cube-based multicast routing algorithms. Our results show that for multicast traffic, the column-path routing offers higher throughputs, while the multipath algorithm offers lower message latencies. Another result of our study is that the commonly implemented simplistic scheme of sending one copy of a multicast message to each of its destinations exhibits good performance provided the number of destinations is small 相似文献
Polysialic acid (PSA) is one of the most abundant glycopolymer present in embryonic brain, and it is known to be involved in key roles such as plasticity in the central nervous system, cell adhesion, migration and localization of neurotrophins. However, in adult brain, its expression is quite low. The exception to this is in Alzheimer′s disease (AD) brain, where significantly increased levels of polysilylated neural cell adhesion molecule (PSA‐NCAM) have been reported. Here, we confirm the role of PSA as a metal chelator, allowing it to decrease cytotoxicity caused by high levels of transition metals, commonly found in AD brain, and as a regulator of cell behavior. UV‐visible (UV‐vis) and circular dichroism (CD) spectroscopy, atomic force microscopy (AFM), and isothermal titration calorimetry (ITC) techniques were used to investigate the assembly of PSA–metals complexes. These PSA–metal complexes exhibited less toxicity compared to free metal ions, and in particular, the PSA–Cu2+ complex synergistically promoted neurite outgrowth in PC12 cells. 相似文献
Polycarbazole (PCz) has been synthesized by chemical oxidation method using APS as an oxidizing agent and PCz/CuO and PCz/Fe2O3 nanocomposites by in situ polymerization method for different wt% of CuO and Fe2O3 at room temperature. XRD patterns confirmed crystalline nature of samples. FTIR indicated strong interaction between PCz and nano fillers. The morphological and optical absorption studies were carried out using SEM and UV–Vis respectively. Addition of CuO or Fe2O3 to PCz decreased its direct and indirect band gaps. However, band gap showed a small change with dopant contents up to 30%. Urbach energy decreased with the addition of dopants. But Urbach energy of the composites increased with increasing dopants content from 10 to 30%. DC conductivity of PCz and its nanocomposites has been measured by following two probe technique in the temperature range 300–423 K. The conductivity of both the nanocomposites is found to be less than the pure PCz and it is found to increase with wt% of CuO or Fe2O3 as the case may be. The activation energy has been determined by fitting Arrhenius expression to the dc conductivity data at high temperature. The activation energy of polycarbazole is determined to be less than that of the composites. In both the composites, activation energy decreased and conductivity increased with the increase of dopant content.
Silicon - This study is an effort to utilize agricultural biomass rice husk for useful applications. The biomass has been milled and then pyrolysed at three different temperatures (800, 900 and... 相似文献