SystemC:一种新的系统建模语言

文章介绍了一种国外正在研究的新的系统建模语言SystemC，因其较好地结合了面向对象的设计方法和硬件建模的特点，从而有望解决系统建模和HW／SW协同设计中等一系列问题。     

A Cooperative Copper Metal–Organic Framework‐Hydrogel System Improves Wound Healing in Diabetes

Chronic nonhealing wounds remain a major clinical challenge that would benefit from the development of advanced, regenerative dressings that promote wound closure within a clinically relevant time frame. The use of copper ions has shown promise in wound healing applications, possibly by promoting angiogenesis. However, reported treatments that use copper ions require multiple applications of copper salts or oxides to the wound bed, exposing the patient to potentially toxic levels of copper ions and resulting in variable outcomes. Herein the authors set out to assess whether copper metal organic framework nanoparticles (HKUST‐1 NPs) embedded within an antioxidant thermoresponsive citrate‐based hydrogel would decrease copper ion toxicity and accelerate wound healing in diabetic mice. HKUST‐1 and poly‐(polyethyleneglycol citrate‐co‐N‐isopropylacrylamide) (PPCN) are synthesized and characterized. HKUST‐1 NP stability in a protein solution with and without embedding them in PPCN hydrogel is determined. Copper ion release, cytotoxicity, apoptosis, and in vitro migration processes are measured. Wound closure rates and wound blood perfusion are assessed in vivo using the splinted excisional dermal wound diabetic mouse model. HKUST‐1 NPs disintegrated in protein solution while HKUST‐1 NPs embedded in PPCN (H‐HKUST‐1) are protected from degradation and copper ions are slowly released. Cytotoxicity and apoptosis due to copper ion release are significantly reduced while dermal cell migration in vitro and wound closure rates in vivo are significantly enhanced. In vivo, H‐HKUST‐1 induced angiogenesis, collagen deposition, and re‐epithelialization during wound healing in diabetic mice. These results suggest that a cooperatively stabilized, copper ion‐releasing H‐HKUST‐1 hydrogel is a promising innovative dressing for the treatment of chronic wounds.     

A Classification System for Reliability Models

There has been little attempt to introduce a general classification system for reliability models analogous to those in other areas of applied probability, notably queueing systems. Thus there has been an unavoidable confusion in the literature and considerable unnecessary duplication of investigative effort. This paper argues the case for a classification system analogous to that in use for queues; identifies necessary features of such a system; and proposes a partial classification system. To be successful such a system must not only be a relatively convenient summary of diverse models, but must have the general support of the reliability community.     

AlxGa1–xN—A New Material System for Biosensors

The applicability of the group III nitride material system for the fabrication of semiconductor‐based biosensors is demonstrated. The operation of ion‐sensitive field‐effect transistors (ISFETs) based on AlGaN/GaN heterostructures in aqueous electrolytes is shown to be characterized by high sensitivity and low drift. Fibroblasts in contact with oxidized and as‐deposited AlGaN surfaces are demonstrated to survive at least for 24 h, indicating that these surfaces are chemically robust and non‐toxic against living cells. Surface hydrophilization using thermal oxidation allows the deposition of highly mobile lipid membranes by vesicle fusion. The homogeneity and the diffusion properties of phospholipids with different net charges were analyzed by fluorescence microscopy and constant photobleaching, taking advantage of the optical transparency of the AlGaN material system. The obtained results reveal that AlGaN‐based devices are promising candidates for future multifunctional biosensors.     

RTOS modeling in SystemC for real-time embedded SW simulation: A POSIX model

SystemC is committed to support the requirements for an integrated, HW/SW co-design flow, thus allowing the development of complex, multiprocessing, Systems-on Chip (MpSoC). To make this possible, efficient modeling and simulation methodologies for Real-Time, Embedded (RT/E) SW in SystemC have to be developed, so that the designer can verify and refine the application SW together with the rest of the elements of the platform. Accurate modeling of the application SW requires an accurate model of the RTOS. Nevertheless, low-level, dynamic timing characteristics of the RTOS such as time-slicing, priority-based preemptive scheduling, interrupts and exceptions do not have a direct implementation in SystemC. In this paper, techniques are proposed to accurately model the detailed RTOS functionality on top of the SystemC execution kernel. The model allows timed-simulation and refinement of the RT/E SW code in SystemC. The simulation technology has been applied to the development of a high-level, POSIX simulation library in SystemC. The library allows the designer a fast, sufficiently accurate, timed simulation of the application SW running on top of POSIX. As most current RTOSs support this standard, the library is portable to different development frameworks. The library provides the required infrastructure for a complete, multiprocessing, HW/SW co-simulation environment at different abstraction levels using SystemC.     

A System of Models for Fluid-Electrolyte Dynamics

In this paper, a number of models which have been developed for studying fluid-electrolyte equilibrium and imbalance is presented. Two levels of dynamics and control are considered corresponding to the physiological processes and the incorporation of such processes within the clinical dynamics of patient care. The large-scale simulations presented are used mainly for hypothesis testing or giving insight into the complex physiological dynamics, whereas the clinical models, which are smaller, are used for parameter estimation and predicting the evolving patient state. Computer simulation is central to these model developments in generating time responses for model identification, validation, and prediction. The paper examines the possible clinical application of the various models in the management of fluid-electrolyte disorders and indicates that features of each of them, integrated into a single implementation, could provide a system of practical clinical value.     

A Framework for Fuzzy Expert System Creation—Application to Cardiovascular Diseases

A methodology for the automated development of fuzzy expert systems is presented. The idea is to start with a crisp model described by crisp rules and then transform them into a set of fuzzy rules, thus creating a fuzzy model. The adjustment of the model's parameters is performed via a stochastic global optimization procedure. The proposed methodology is tested by applying it to problems related to cardiovascular diseases, such as automated arrhythmic beat classification and automated ischemic beat classification, which, besides being well-known benchmarks, are of particular interest due to their obvious medical diagnostic importance. For both problems, the initial set of rules was determined by expert cardiologists, and the MIT-BIH arrhythmia database and the European ST-T database are used for optimizing the fuzzy model's parameters and evaluating the fuzzy expert system. In both cases, the results indicate an escalation of the performance from the simple initial crisp model to the more sophisticated fuzzy models, proving the scientific added value of the proposed framework. Also, the ability to interpret the decisions of the created fuzzy expert systems is a major advantage compared to "black box" approaches, such as neural networks and other techniques.     

Millimeter-Wave Identification—A New Short-Range Radio System for Low-Power High Data-Rate Applications

The radio-frequency identification (RFID) concept is expanded to millimeter-wave frequencies and millimeter-wave identification (MMID) in this paper. The MMID concept and a comparison with UHF RFID are presented, showing the limitations and benefits of MMID. Three feasible applications are suggested for MMID, which are: (1) wireless mass memory; (2) an automatic identification system with pointing functionality; and (3) transponder communication with automotive radar. To demonstrate the feasibility of the MMID system, experimental results for both downlink and backscattering-based uplink are presented at 60 GHz.     

QSynth-TopK:一个支持Top K查询的质量敏感的自动服务组合系统

质量敏感的自动服务组合旨在根据用户的输入输出请求和服务质量约束,从海量的Web服务中快速搜索满足要求的最优组合方案,能够有效应用于服务组合辅助建模、正确性校验等领域.为了向用户提供更多的组合方案,以满足多样化的应用需求,并消除由于集中选择最优方案所带来的性能瓶颈隐患,我们在QSynth系统的基础上开发了一个支持top k查询的系统——QSynth-TopK.该系统通过对最优组合方案中的服务进行迭代地替换,实现全局服务质量的有序递减,以得到组合质量排名前k个的服务组合方案.理论证明该算法具有可靠的精确性,实验证明系统在大规模服务集上有着良好的、稳定的运行效率.     

Current Sensing for Automotive Electronics—A Survey

Current sensing is widely used in power electronic applications such as dc-dc power converters and adjustable-speed motor drives. Such power converters are the basic building blocks of drivetrains in electric, hybrid, and plug-in hybrid electric vehicles. The performance and control of such vehicles depend on the accuracy, bandwidth, and efficiency of its sensors. Various current-sensing techniques based on different physical effects such as Faraday's induction law, Ohm's law, Lorentz force law, the magnetoresistance effect, and the magnetic saturation effect are described in this paper. Each technique is reviewed and examined. The current measurement methods are compared and analyzed based on their losslessness, simplicity, and ease of implementation.     

Metrics for packet reordering—A comparative analysis

Packet reordering is an inevitable phenomenon on the Internet. An ideal metric for packet reordering should capture reordering accurately, provide insight into the nature of reordering, and help in the evaluation and analysis of reordering leading to mitigation of its adverse effects. Proposed metrics for packet reordering, namely, reorder density, reorder buffer‐occupancy density, reordering extent, and n‐reordering, overcome to various degrees the deficiencies of percentage reordering in capturing the nature and extent of reordering. These metrics vary widely in areas such as evaluation complexity, measurement technique, usage, and in the definition used for packet reordering itself. Metrics for reordering are evaluated using a framework consisting of a set of both essential and desirable attributes of reorder metrics. The attributes include the ability to capture reordering, sensitivity to lost and duplicate packets in reorder measurements, usefulness, simplicity, and evaluation complexity. Finally, the characterization of packet reordering using these metrics is discussed, using sets of measurements carried over the Internet. Copyright © 2007 John Wiley & Sons, Ltd.     

Atomistic Simulation of Realistically Sized Nanodevices Using NEMO 3-D—Part I: Models and Benchmarks

Device physics and material science meet at the atomic scale of novel nanostructured semiconductors, and the distinction between new device or new material is blurred. Not only the quantum-mechanical effects in the electronic states of the device but also the granular atomistic representation of the underlying material are important. Approaches based on a continuum representation of the underlying material typically used by device engineers and physicists become invalid. Ab initio methods used by material scientists typically do not represent the band gaps and masses precisely enough for device design, or they do not scale to realistically large device sizes. The plethora of geometry, material, and doping configurations in semiconductor devices at the nanoscale suggests that a general nanoelectronic modeling tool is needed. The 3-D NanoElectronic MOdeling (NEMO 3-D) tool has been developed to address these needs. Based on the atomistic valence force field and a variety of nearest neighbor tight-binding models (e.g., s, sp³s*, and sp³d⁵s*), NEMO 3-D enables the computation of strain and electronic structure for more than 64 and 52 million atoms, corresponding to volumes of (110 nm)³ and (101 nm)³, respectively. The physical problem may involve very large scale computations, and NEMO 3-D has been designed and optimized to be scalable from single central processing units to large numbers of processors on commodity clusters and supercomputers. NEMO 3-D has been released with an open-source license in 2003 and is continually developed by the Network for Computational Nanotechnology (NCN). A web-based online interactive version for educational purposes is freely available on the NCN portal ( http://www.nanoHUB.org). In this paper, theoretical models and essential algorithmic and computational components that have been used in the development and successful deployment of NEMO 3-D are discussed.     

ACCNT—A Metallic-CNT-Tolerant Design Methodology for Carbon-Nanotube VLSI: Concepts and Experimental Demonstration

We demonstrate ACCNT (pronounced as “accent”), a solution to the metallic-nanotube problem that does not require any metallic-nanotube removal of any kind. ACCNT uses asymmetrically correlated carbon nanotubes to achieve metallic-nanotube tolerance, delivering high on– off ratios $(hbox{10}^{4}{-} hbox{10}^{6})$ while preserving the current drive. In addition, this metallic-nanotube tolerance can be engineered arbitrarily close to 100%. We present the ACCNT concepts in detail, verifying the concepts and underlying assumptions via experimental results. We further demonstrate inverters using ACCNT and ACCNT scalability to a wafer scale. ACCNT marks the first demonstration of a VLSI-compatible metallic-nanotube-tolerant design methodology.      

FPGA-Based Current Controllers for AC Machine Drives—A Review

The aim of this paper is to present the interest of implementing digital controllers using field-programmable gate array (FPGA) components. To this purpose, a variety of current control techniques, which is applied to alternating current machine drives, is designed and implemented. They consist of on-off current controllers, proportional-integral current controller, and predictive current controller. The quality of the regulated current is significantly improved. It is mainly due to a very important reduction of the execution time delay. Indeed, in all described techniques, the execution time of the designed hardware architectures is only a few microseconds. This time reduction derives directly from the possibility offered by FPGAs to design very powerful dedicated architectures. Numerous experimental results are given in order to illustrate the efficiency of FPGA-based solutions to achieve high-performance control of electrical systems.     

MICRON—A Framework for Connection Establishment in Optical Networks

Traffic grooming in optical networks has gained significance due to the prevailing sub-wavelength requirement of end users. Optical networks get upgraded to the latest technology slowly with time with only a subset of nodes being upgraded to the latest technology. The networks are thus comprised of nodes employing heterogeneous switching architectures. In this paper, we develop a framework called Methodology for Information Collection and Routing in Optical Networks (MICRON) for connection establishment in optical grooming networks with heterogeneous switching architectures. We illustrate with examples the information that may be collected from the links, and operators that may be used to obtain information along a path. The information can be used to select a path dynamically depending on the network status. We complete the MICRON framework by providing a generic channel assignment procedure that could be employed to implement different channel assignment schemes. Various routing and channel assignment algorithms can be developed from the proposed framework. The framework may be easily implemented with simple traffic engineering extensions to the already existing routing protocols in the wide-area networks.     

A Monte Carlo Technique for Obtaining System Reliability Confidence Limits from Component Test Data

A digital computer technique is developed, using a Monte Carlo simulation based on common probability models, with which component test data may be translated into approximate system reliability limits at any confidence level. The probability distributions from which the component failures are assumed to come are the exponential, Weibull (shape parameter K known), gamma (shape parameter ? known), normal, and lognormal. The components can be arranged in any system configuration, series, parallel, or both. Since reliability prediction is meaningful only when expressed with an associated confidence leve, this method provides a valuable and economical tool for the reliability analyst.     

A 32 Mbit/s Component Separation DPCM Coding System for NTSC Color TV

A component separation DPCM Coding system is described which is capable of transmitting a 4 MHz NTSC color TV signal with broadcast quality at a 32.064 Mbit/s rate. The input NTSC color TV signal is first separated into a luminance componentYand two chrominance componentsIandQ. Then, these three components are converted into a TDM-PCM color signal, whereIandQof only odd lines are transmitted and samples in horizontal blanking intervals ofY,I,andQare removed, in order to reduce the transmission rate. This TDM-PCM signal is encoded by a single DPCM coder, which employs a two-dimensional prediction method and a dual word-length coding method. For theYsignal, 4 bit and 8 bit code words are assigned to 29 quantizing levels. For bothIandQsignals, 3 bit and 6 bit code words are assigned to 13 quantizing levels. Coding experiment results show that this coding system is promising for application to broadcast color TV signal transmission at a 32.064 Mbit/s rate.     

The Matrix Balun—A Transistor-Based Module for Broadband Applications

In this paper the analysis and design of a new active balun with very broadband performance, the matrix balun, are reported. Measured results show a common mode rejection ratio, CMRR, larger than 15 dB between 4 and 42 GHz while exhibiting 2 dB single-ended gain with a ripple of 1 dB. The balun was realized in a 0.15 mum GaAs mHEMT process. It occupies a chip area of 0.63 mm² and consumes a dc power of 20 mW. The same matrix balun circuit may also be biased for amplification and used as a matrix amplifier. The circuit then exhibits 10.5 dB gain up to 63 GHz with 1 dB ripple above 5.5 GHz and a power consumption of 67 mW.