Exponential flux-controlled memristor model and its floating emulator

As commercial memristors are still unavailable in the market, mathematic models and emulators which can imitate the features of the mernristor are meaningful for further research. In this paper, based on the analyses of characteristics of the q-φ curve, an exponential flux-controlled model, which has the quality that its memductance （memristance） will keep monotonically increasing or decreasing unless the voltage＇s polarity reverses （if not approach the boundaries）, is constructed. A new approach to designing the floating emulator of the memristor is also proposed. This floating structure can flexibly meet various demands for the current through the memristor （especially the demand for a larger current）. The simulations and experiments are presented to confirm the effectiveness of this model and its floating emulator.

Effective Capacity in Cognitive Radio Networks with Relay and Primary User Emulator

In this paper,the transmission performances are studied in cognitive radio networks with primary user emulator and relay existence.In the proposed network,the users include primary users,secondary users and primary user emulators.The decreasing access priority of the users are primary users,primary user emulators and secondary users.Different user access to the network results in different transmission effects.We impose interference power constraints on the secondary users to protect the primary users from being interfered.We also adopt the transmission mechanism that transits among more than one secondary transmitters,secondary receivers and relays.The transition models of the transmission states are proposed to describe the transmission mechanism.To investigate the transmission performances,the theory of effective capacity is adopted.The transmission performances in terms of effective capacity are expressed and demonstrated under different transmission policies.The overall effective capacity,as the overall data traffic in the cognitive radio network,is calculated.Besides,the overall effective capacity is demonstrated under different transmission strategies.The results show the greedy transmission strategy outperforms the rest of the transmission 8 policies in the overall effective capacity.For a larger number of the users,the effective capacity converges to a certain value.

Suppression of ferroresonance using passive memristor emulator

Power system inherently consists of capacitance and inductance in its components. Equipment with saturable inductance and circuit capacitance provides circumstances of generating ferroresonance, resulting in overvoltage and overcurrent in the connected system. The effects of ferroresonance result in insulation failure and hence damage to the equipment is unavoidable. Though many devices are proposed for mitigating such circumstances, a promising technology of using memristors may provide better performance than others in the future. A memristor emulator using the N-channel JFET J310 is used in this work. Unlike other electronic components that replicate memristor properties, the chosen memristor emulator is a passive device since it does not need any external power supply. Simulation and experimental results verify the design of a memristor emulator and the characteristics of an ideal memristor. Experimental results prove that the memristor emulator can suppress the fundamental ferroresonance induced in a prototype single phase transformer. The results of the harmonic analysis also validate the memristor performance against the conventional technique.

Inverter-Based Diesel Generator Emulator for the Study of Frequency Variations in a Laboratory-Scale Autonomous Power System

This paper presents the modeling, simulation and practical implementation of an inverter-based diesel generator emulator. The main purpose of this emulator is for the study of frequency variations in diesel-based autonomous power systems in a laboratory environment where the operation of a real diesel generator is not possible. The emulator basically consists in a voltage source inverter with a second order output filter which voltage references are given by the model of the diesel generator. The control of the emulator is based on the digital signal processor TMS320F2812, where the mathematical models of the diesel generator and the control of the inverter are computed in real-time. Parameters for the model were obtained from commercially available components. Experimental results for different values of speed droop showed that the emulator achieves a satisfactory performance in the transient and stationary response. For the stationary response, the measured frequency deviates from theoretical values with a mean absolute error of: 0.06 Hz for 0% droop, 0.037 Hz for 3% droop, and 0.087 Hz for 5% droop. For the transient response, the measured frequency nadir deviates from simulations in: 0.05 Hz for 0% droop, 0.02 Hz for 3% droop, and 0.1 Hz for 5% droop.

Assessment of Quality of Experience (QoE) of Web and Video Services over a Mobile Network Using a Network Emulator

This paper investigates the subjective assessment of QoE of web and video services over a mobile network. To achieve this, the authors used the network emulator (NetEm) traffic control functionality to simulate the dynamic behaviour of a mobile network. Experiments were conducted in a laboratory setting and test conditions were varied to ascertain the QoE, with a focus on QoE metrics such as delay and packet loss ratio. From the experiments conducted, it was observed that there was a negative correlation between delay and average mean opinion score (MOS), and between packet loss ratio and average MOS. The results obtained can be adopted by network operators to provide better services which would lead to improved subscriber base and profitability for the operators and better QoE for the end users.

A Massively Parallel Re-Configurable Mesh Computer Emulator: Design, Modeling and Realization

Emulating massively parallel computer architectures represents a very important tool for the parallel programmers. It allows them to implement and validate their algorithms. Due to the high cost of the massively parallel real machines, they remain unavailable and not popular in the parallel computing community. The goal of this paper is to present an elaborated emulator of a 2-D massively parallel re-configurable mesh computer of size n x n processing elements (PE). Basing on the object modeling method, we develop a hard kernel of a parallel virtual machine in which we translate all the physical properties of its different components. A parallel programming language and its compiler are also devel-oped to edit, compile and run programs. The developed emulator is a multi platform system. It can be installed in any sequential computer whatever may be its operating system and its processing unit technology (CPU). The size n x n of this virtual re-configurable mesh is not limited;it depends just on the performance of the sequential machine supporting the emulator.

A novel inertia emulator to reduce the rate of change of frequency for power systems with solar PV and battery energy storage

Energy access,climate change and public health issues are some major drivers for the need for renewable sources.However,most renewable sources,excluding large hydro,have zero or negligible rotational inertia,which is critical to stabilizing the power system after contingency.Therefore,this paper proposes a droop-based inertia emulator to reduce the rate of change of frequency and frequency deviations.The robustness of the controller is analysed by applying various uncertainties and disturbances of power system components that were carried out using DIgSILENT PowerFactory simulations.The obtained results are compared with existing literature and the desired performance shows an improvement in the rate of change of frequency of 34.78%for an IEEE 6-bus system,24.32%for a 12-bus system and 18%for a 39-bus system.

MetaCity: An Edge Emulator with the Feature of Realistic Geospatial Support for Urban Computing

The edge computing paradigm is an important supplement to the traditional cloud computing paradigm in current IoT application scenarios.However,edge computing is highly related to a specific application scenario,in which the mobility of edge devices and the geographical distribution of edge infrastructure are strongly correlated.However,it is expensive to deploy the solution in the real world and most current edge computing emulators lack realistic scenario support and mobility support.Therefore,it is challenging to evaluate whether an edge infrastructure deployment solution can satisfy the QoS(Quality-of-Service)requirement of an edge application in a cost-effective manner.In this paper,we propose and implement an edge emulator,MetaCity,which is able to effectively enforce edge computing policies and construct realistic application scenarios.MetaCity can leverage geographical data to establish an emulation environment according to the realistic infrastructure deployment strategy and emulate the mobility process of edge devices based on the actual urban road network.MetaCity can also provide an extensible network QoS monitoring module that supports the concurrent execution of various QoS monitoring in an emulated environment.In addition,MetaCity provides a user-friendly web-based graphical user interface instead of text-based configuration files.For evaluation,three smart transportation-based experiments are conducted to validate the functionality,scalability,and emulation accuracy of MetaCity.

Design and Implementation of SCSI Target Emulator

A SCSI target emulator is used in a storage area network （SAN） environment to simulate the behavior of a SCSI target for processing and responding to I/O requests issued by initiators. The SCSI target emulator works with general storage devices with multiple transport protocols. The target emulator utilizes a protocol conversion module that translates the SCSI protocols to a variety of storage devices and implements the multi-RAID-level configuration and storage visualization functions. Moreover, the target emulator implements RAM caching, multi-queuing, and request merging to effectively improve the I/O response speed of the general storage devices. The throughput and average response times of the target emulator for block sizes of 4 KB to 128 KB are 150% faster for reads and 67% faster for writes than the existing emulator. With a block size of 16 KB, the I/O latency of the target emulator is only about 20% that of the existing emulator.

Novel Variable PDL Emulator Based on LiNbO_3 Modulator

We propose and demonstrate a novel variable PDL emulator based on a LiNbO3 modulator. The proposed emulator could vary the PDL values simply by adjusting the bias voltage of modulator. The results show that the proposed PDL emulator could generate a wide range of PDL values (0 ~ 35 dB). The generated PDL value could be maintained within ±0.02 dB for >70 minutes. The wavelength dependency was about 0.03 dB in the range of 1520 nm~ 1590 nm.

A fast and simple system performance emulator for enhanced solid state disks:a case study of long read operations

In this paper, we propose a fast and simple system emulator, called a system performance emulator(SPE), to evaluate long read operations.The SPE estimates how much system-wide performance is enhanced by using a faster solid state disk(SSD).By suspending a CPU for a certain time during direct memory access(DMA) transfer and subtracting this suspended time from the total DMA time, the SPE estimates the improvement in system performance expected from an enhanced SSD prior to its manufacture.We also examine the relation between storage performance and system performance using the SPE.

Condition monitoring of a wind turbine generator using a standalone wind turbine emulator

The intend of this paper is to give a description of the realization of a low-cost wind turbine emulator （WTE） with open source technology from graze required for the condition monitoring to diagnose rotor and stator faults in a wind turbine generator （WTG）. The WTE comprises of a 2.5 kW DC motor coupled with a 1 kW squirrel-cage induction machine. This paper provides a detailed overview of the hardware and software used along with the WTE control strategies such as MPPT and pitch control. The emulator reproduces dynamic characteristics both under step variations and arbitrary variation in the wind speed of a typical wind turbine （WT） of a wind energy conversion system （WECS）. The usefulness of the setup has been benchmarked with previously verified WT test rigs made at the University of Manchester and Durham University in UK. Considering the fact that the rotor blades and electric subassemblies direct drive WTs are most susceptible to damage in practice, generator winding faults and rotor unbalance have been introduced and investigated using the terminal voltage and generated current. This wind turbine emulator （WTE） can be reconfigured or analyzed for condition monitoring without the need for real WTs.

A Systematic Design of Emulators for Multivariable Non Square and Nonlinear Systems

In this paper, multimodel and neural emulators are proposed for uncoupled multivariable nonlinear plants with unknown dynamics. The contributions of this paper are to extend the emulators to multivariable non square systems and to propose a systematic method to compute the multimodel synthesis parameters. The effectiveness of the proposed emulators is shown through two simulation examples. The obtained results are very satisfactory, they illustrate the performance of both emulators and show the advantages of the multimodel emulator relatively to the neural one.

Detecting Vulnerability on IoT Device Firmware: A Survey

Internet of things (IoT) devices make up 30%of all network-connected endpoints,introducing vulnerabilities and novel attacks that make many companies as primary targets for cybercriminals.To address this increasing threat surface,every organization deploying IoT devices needs to consider security risks to ensure those devices are secure and trusted.Among all the solutions for security risks,firmware security analysis is essential to fix software bugs,patch vulnerabilities,or add new security features to protect users of those vulnerable devices.However,firmware security analysis has never been an easy job due to the diversity of the execution environment and the close source of firmware.These two distinct features complicate the operations to unpack firmware samples for detailed analysis.They also make it difficult to create visual environments to emulate the running of device firmware.Although researchers have developed many novel methods to overcome various challenges in the past decade,critical barriers impede firmware security analysis in practice.Therefore,this survey is motivated to systematically review and analyze the research challenges and their solutions,considering both breadth and depth.Specifically,based on the analysis perspectives,various methods that perform security analysis on IoT devices are introduced and classified into four categories.The challenges in each category are discussed in detail,and potential solutions are proposed subsequently.We then discuss the flaws of these solutions and provide future directions for this research field.This survey can be utilized by a broad range of readers,including software developers,cyber security researchers,and software security engineers,to better understand firmware security analysis.

Adaptive Emulation Framework for Multi-Architecture IoT Firmware Testing

Internet of things(IoT)devices are being increasingly used in numerous areas.However,the low priority on security and various IoT types have made these devices vulnerable to attacks.To prevent this,recent studies have analyzed firmware in an emulation environment that does not require actual devices and is efficient for repeated experiments.However,these studies focused only on major firmware architectures and rarely considered exotic firmware.In addition,because of the diversity of firmware,the emulation success rate is not high in terms of large-scale analyses.In this study,we propose the adaptive emulation framework for multi-architecture(AEMA).In the field of automated emulation frameworks for IoT firmware testing,AEMA considers the following issues:(1)limited compatibility for exotic firmware architectures,(2)emulation instability when configuring an automated environment,and(3)shallow testing range resulting from structured inputs.To tackle these problems,AEMAcan emulate not onlymajor firmware architectures but also exotic firmware architectures not previously considered,such as Xtensa,ColdFire,and reduced instruction set computer(RISC)version five,by implementing a minority emulator.Moreover,we applied the emulation arbitration technique and input keyword extraction technique for emulation stability and efficient test case generation.We compared AEMA with other existing frameworks in terms of emulation success rates and fuzz testing.As a result,AEMA succeeded in emulating 864 out of 1,083 overall experimental firmware and detected vulnerabilities at least twice as fast as the experimental group.Furthermore,AEMAfound a 0-day vulnerability in realworld IoT devices within 24 h.

On Dynamic Channel Emulation in Sector MPAC for Over-the-Air Testing of Beamformed Massive MIMO Devices

In this article,novel emulation strategies for the sectored multiple probe anechoic chamber(SMPAC)are proposed to enable the reliable evaluation of the massive multiple-input multiple-output(MIMO)device operating at beamforming mode,which requires a realistic non-stationary channel environment.For the dynamic propagation emulation,an efficient closed-form probe weighting strategy minimizing the power angular spectrum(PAS)emulation errors is derived,substantially reducing the associated computational complexity.On the other hand,a novel probe selection algorithm is proposed to reproduce a more accurate fading environment.Various standard channel models and setup configurations are comprehensively simulated to validate the capacity of the proposed methods.The simulation results show that more competent active probes are selected with the proposed method compared to the conventional algorithms.Furthermore,the derived closedform probe weighting strategy offers identical accuracy to that obtained with complicated numerical optimization.Moreover,a realistic dynamic channel measured in an indoor environment is reconstructed with the developed methodologies,and 95.6%PAS similarity can be achieved with 6 active probes.The satisfactory results demonstrate that the proposed algorithms are suitable for arbitrary channel emulation.

Performance Evaluation of Topologies for Multi-Domain Software-Defined Networking

Software-defined networking(SDN)is widely used in multiple types of data center networks,and these distributed data center networks can be integrated into a multi-domain SDN by utilizing multiple controllers.However,the network topology of each control domain of SDN will affect the performance of the multidomain network,so performance evaluation is required before the deployment of the multi-domain SDN.Besides,there is a high cost to build real multi-domain SDN networks with different topologies,so it is necessary to use simulation testing methods to evaluate the topological performance of the multi-domain SDN network.As there is a lack of existing methods to construct a multi-domain SDN simulation network for the tool to evaluate the topological performance automatically,this paper proposes an automated multi-domain SDN topology performance evaluation framework,which supports multiple types of SDN network topologies in cooperating to construct a multi-domain SDN network.The framework integrates existing single-domain SDN simulation tools with network performance testing tools to realize automated performance evaluation of multidomain SDN network topologies.We designed and implemented a Mininet-based simulation tool that can connect multiple controllers and run user-specified topologies in multiple SDN control domains to build and test multi-domain SDN networks faster.Then,we used the tool to perform performance tests on various data center network topologies in single-domain and multi-domain SDN simulation environments.Test results show that Space Shuffle has the most stable performance in a single-domain environment,and Fat-tree has the best performance in a multi-domain environment.Also,this tool has the characteristics of simplicity and stability,which can meet the needs of multi-domain SDN topology performance evaluation.

基于动态仿真的独立ICS小车行李系统设计

本文将动态仿真引入独立ICS小车行李系统的设计过程,通过仿真控制策略分析优化行李系统布局;通过建立基于Emulate3D的仿真模型,动态仿真独立ICS小车行李系统关键点流量、系统内时间、早到行李量以及不同状态托盘的实时分布等数据特性;验证了行李系统设计的合理性;解决了静态计算分析难以处理的,诸如基于航班波次的行李系统性能评估及不同故障模式下行李系统保障能力评估等难题。

SoC软硬件协同验证技术的应用研究

介绍了软硬件协同验证的原理,给出了笔者在实际SoC开发中采用的四种软硬件协同验证方案。根据软硬件协同仿真原理提出CFM方案。对几种方案进行比较,并提出在实际SoC设计中选取软硬件协同验证方案的建议。