Burn Rate Models for Gun Propellants

In the past, Vieille's law and minor modifications of it described sufficiently the linear burning rate of gun propellants which governs the design of charges by interior ballistic simulations. Recent developments to increase the performance led to new gun concepts and innovative propellants. These are the electrothermal‐chemical gun, porous and foamed charges as well as formulations exhibiting a temperature independent burning. Vieille's law cannot fully meet experimental results in these cases. Approaches based on the heat flow equation in the solid energetic material give simplified formulas to extend the validity. These burning rate models have the ability to describe the experimentally determined burning behavior at least in a simplified or qualitative way. More sophisticated methods consider complex geometrical structures in the solid or take into account the actual progress in phase behavior and reaction kinetics of heterogeneous combustion. The dependence of the burning rate on initial temperature, on phase transitions, porous structure and gaseous reactions can be described.     

Untargeted Metabolite Profiling of Abalone Using Gas Chromatography Mass Spectrometry

Abalone meat is a delicacy worldwide, fetching high prices and a valuable source of income for the many countries farming and exporting this commodity. The quality of abalone is based on its unique sensory properties and an analytical metabolomics method for determining the compounds related to this would serve as a valuable tool for ensuring quality and consumer satisfaction. Metabolomics is a promising “omics” tool which can be applied towards this goal; however, widely applicable parameters for the evaluation of an untargeted gas chromatography mass spectrometry (GC-MS) metabolomic approach is still lacking. GC-MS is a popular and suitable metabolomics method due to its high separation power, reproducible retention times, and selective mass detection. The aim of this study was to establish a reliable untargeted GC-MS method for analyzing firstly a standard compound mixture consisting of 10 compounds representing various compound classes and secondly applying the method in an untargeted manner to abalone muscle samples. Using a standard compound mixture with a concentration range of 1 to 100 μg/mL, the limit of detection (LOD) ranged between 0.01 and 3.30 μg/mL, the limit of quantification (LOQ) resulted in values between 0.02 and 9.49 μg/mL, the accuracy determined was <1.5 μg/mL, and the precision displayed a coefficient of variance (CV) <25 %. When evaluating the method in terms of biological samples harvested, the repeatability and intermediate precision showed CV values <50 % for most compounds measured, allowing application of this method for metabolite profiling of abalone to answer important biological questions.     

Joint power control and intracell scheduling of DS-CDMA nonrealtime data

The performance of DS-CDMA systems depends on the success in managing interference arising from both intercell and intracell transmissions. Interference management in terms of power control for real time data services like voice has been widely studied and shown to be a crucial component for the functionality of such systems. In this work we consider the problem of supporting downlink nonreal time data services, where in addition to power control, there is also the possibility of controlling the interference by means of transmission scheduling. One such decentralized schedule is to use time division so that users transmit in a one-by-one fashion within each cell. We show that this has merits in terms of saving energy and increasing system capacity. We combine this form of intracell scheduling with a suggested distributed power control algorithm for the intercell interference management. We address its rate of convergence and show that the algorithm converges to a power allocation that supports the nonreal time data users, using the minimum required power while meeting requirements on average data rate. Numerical results indicate a big potential of increased capacity and that a significant amount of energy can be saved with the proposed transmission scheme     

On stress induced leakage current in 5 and 3 nm thick oxides

The stress induced leakage current (SILC) in Si/SiO₂ structures with thin gate oxides has a steady-state component which increases drastically when the oxide thickness decreases. It is generally agreed that the SILC is due to electron tunnelling trough stress-induced traps. However, it was observed that the SILC, created by Fowler–Nordheim injection, decays continuously when, after stress, the samples are positively or negatively biased at a low voltage. The decay is irreversible as long as the gate oxide is not biased at a high voltage. The present article adds complementary observations. It shows, first that the above phenomenon is observed in 3.5 nm thick oxides, secondly, that this phenomenon is stable as long as the temperature stays below 200°C, and thirdly, that during the SILC decay, the interface state density does not diminish.     

Capacity allocation and channel assignment in cellular radio systems using reuse partitioning

Reuse partitioning is a technique for providing more efficient spectrum reuse in cellular radio systems. A cell in such a system is divided into concentric zones, each associated with an overlaid cell plan. For these schemes an optimum channel assignment strategy is proposed. Numeric examples show capacity improvements of about 50% compared to conventional systems.<>     

Soft and safe admission control in cellular networks

We study the mobile admission control problem in a cellular PCS network where transmitter powers are constrained and controlled by a distributed constrained power control (DCPC) algorithm. Receivers are subject to nonnegligible noise, and the DCPC attempts to bring each receiver's CIR (carrier-to-interference ratio) above a given quality target. Two classes of distributed admission control are considered. One is a noninteractive admission control (N-IAC), where an admission decision is instantaneously made based on the system state. The other is an interactive admission control (IAC), under which the new mobile is permitted to interact with one or more potential channels before a decision is made. The algorithms are evaluated with respect to their execution time and their decision errors. Two types of errors are examined: type I error, where a new mobile is erroneously accepted and results in outage; and type II error, where a new mobile is erroneously rejected and results in blocking. The algorithms in the N-IAC class accept a new mobile if and only if the uplink and the downlink interferences are below certain corresponding thresholds. These algorithms are subject to errors of type I and type II. In the IAC class, we derive a soft and safe (SAS) admission algorithm, which is type I and type II error free, and protects the CIR's of all active links at any moment of time. A fast-SAS version, which is only type I error-free, is proposed for practical implementation, and is evaluated in several case studies     

Transplantation of hematopoietic stem cells. II: Indications for transplantation of hematopoietic stem cells after myeloablative therapy

The destruction of hematopoiesis and lymphopoiesis by total body irradiation or high dose chemotherapy for the treatment of malignancy can be reversed by the transplantation of allogeneic or autologous hematopoietic stem cells. In primary disorders of bone marrow or immune system, allogeneic stem cells replace deficient cells. Acute leukemias can be cured, with in 50 to 80% disease free survival after 5 to 8 years. The allogeneic graft versus leukemia effect by immunoreactive cells reduces the relapse rate in myeloid and lymphoid malignancies. 40 to 70% of patients with chronic myeloid leukemia remain disease free after more than 5 years. Patients with malignant lymphoma have a 40 to 70% chance of cure with autologous transplantation, which is not increased by allogeneic cells, because of a higher incidence of severe complications. An increasing number of patients without option for cure is treated with the aim of prolonging remission or retarding disease progression, such as in chronic myeloid leukemia, multiple myeloma and certain solid tumors. New studies suggest in breast cancer with axillary lymph node metastases, that adjuvant high dose chemotherapy with autologous stem cell support will significantly improve disease free survival from 30 to over 60% after 3 to 5 years. In congenital metabolic and storage diseases deficient enzymes are substituted by the allogeneic cells. Clinical trials explore the use of stem cell transplantation after myeloablative therapy in autoimmune disorders as well as in gene therapy with transfected hematopoietic stem cells.     

On the Isothermal Martensitic Transformation in 3Y-TZP

The martensitic tetragonal ( t ) → monoclinic ( m ) transformation in 3Y-TZP displays both athermal and isothermal kinetics; both are stress-assisted. Room-temperature transformation was induced with Vickers indentations; the isothermal, or thermally activated, component was induced by annealing indented samples at temperatures up to ∼ 900 K. The reverse m → t transformation occurred on annealing at still higher temperatures. The extent of transformation in the indented region was quantified with Raman microprobe spectroscopy, while the deformation associated with the transformed regions was evident as surface displacements around the indent. The spatial distribution of the transformation product(s) around the indents is complex and not yet entirely understood.     

Remote sensing of the Earth's atmosphere from space with high-resolution Fourier-transform spectroscopy: development and methodology of data processing for the Atmospheric Trace Molecule Spectroscopy experiment

The methodology of spectroscopic remote sensing with high-resolution Fourier-transform spectra obtained from low Earth orbit by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment is discussed. During the course of the Atmospheric Laboratory for Applications and Science (ATLAS) shuttle missions (1992-1994) a flexible, yet reproducible, retrieval strategy was developed that culminated in the near-real-time processing of telemetry data into vertical profiles of atmospheric composition during the ATLAS-3 mission. The development, evolution, robustness, and validation of the measurements are presented and assessed with a summary comparison of trace-gas observations within the Antarctic polar vortex in November 1994.     

Belief‐rule‐based expert systems for evaluation of e‐government: a case study

Little knowledge exists on the impact and results associated with e‐government projects in many specific‐use domains. Therefore, it is necessary to evaluate the efficiency and effectiveness of e‐government systems. Because the development of e‐government is a continuous process of improvement, it requires continuous evaluation of the overall e‐government system as well as evaluation of its various dimensions such as determinants, characteristics and results. E‐government development is often complex, with multiple stakeholders, large user bases and complex goals. Consequently, even experts have difficulties in evaluating these systems, especially in an integrated and comprehensive way, as well as on an aggregate level. Expert systems are a candidate solution to evaluate such complex e‐government systems. However, it is difficult for expert systems to cope with uncertain evaluation data that are vague, inconsistent, highly subjective or in other ways, challenging to formalize. This paper presents an approach that can handle uncertainty in e‐government evaluation: the combination of Belief Rule Base knowledge representation and Evidential Reasoning. This approach is illustrated with a concrete prototype, known as the Belief Rule Based Expert System (BRBES) and implemented in the local e‐government of Bangladesh. The results have been compared with a recently developed method of evaluating e‐government, and it is demonstrated that the results of the BRBES are more accurate and reliable. The BRBES can be used to identify the factors that need to be improved to achieve the overall aim of an e‐government project. In addition, various ‘what if’ scenarios can be generated, and developers and managers can obtain a foretaste of the outcomes. Thus, the system can be used to facilitate decision‐making processes under uncertainty.