反辐射导弹对抗技术研究

反辐射导弹（ARM）技术的迅速发展,给防空系统中的各类雷达及其它辐射源造成了极大威胁。基于对ARM局限性的分析,从雷达体制、技术及战术应用等方面研究了如何对抗反辐射导弹,并针对ARM的发展提出了一些新想法。     

强激光的计算模拟:平顶高斯光束模型

基于广义惠更斯－菲涅耳衍射积分,将平顶高斯光束作为一个整体光束,对其基本性质和变换特性作了统一研究。推导出了平顶高斯光束通过有线性增益（损耗）的近轴ABCD光学系统、无光阑和有光阑ABCD光学系统后解析形式的传输方程。对平顶高斯光束的相似变换以及与超高斯光束的一致性也作了分析。所得结果对强激光的模拟提供了一个有用的计算模型。     

SDN-based architecture for providing quality of service to high-performance distributed applications

The specification of quality of service (QoS) requirements in most of the existing networks is still challenging. In part, traditional network environments are limited by their high administrative cost, although software-defined networks (SDNs), a newer network paradigm, simplify the management of the whole network infrastructure. In fact, SDN provides a simple way to effectively develop QoS provisioning mechanisms. In this sense, we explore the SDN model and its flexibility to develop a QoS provisioning architecture. Through the use of our new architecture, network operators are able to specify QoS levels in a simple way. Each individual data flow can be addressed, and the architecture we propose also negotiates the QoS requirements between the network controller and applications. On the other hand, the network controller continuously monitors the network environment. Then, it allocates network elements resources and prioritizes traffic, adjusting the network performance. We evaluate the feasibility of our QoS provisioning mechanism by presenting three experimental setups under realistic scenarios. For example, for a given scenario where we evaluate file transfers, our results indicate that the additional SDN modules present negligible overhead. Moreover, for a given setup, we observe a reduction of up to 82% in the file transfer times.     

CCD focal-plane image reorganization processors for lossless imagecompression

Four image reorganization ICs that enable real-time difference encoding for hierarchical lossless image compression are reported. Two image reorganization processors are realized on the focal-plane and two are designed for hybridization to a separate imager IC. The two focal-plane ICs represent the first integration of a 256×256 buried-channel frame-transfer CCD image sensor with additional charge-domain circuitry to enable image reformatting at video rates (28 frames/s). The four ICs generate pyramidal pixel output in 3×3 blocks with the center pixel first. Pixel data reorganization is performed through simultaneous readout of three rows of data, followed by pixel resequencing and sampling to provide differential output. A novel architecture provides simultaneous readout of multiple imager rows on the focal-plane ICs. The ICs have achieved a charge-transfer efficiency (CTE) of 0.99996 in the conventional horizontal and vertical CCD registers, and a CTE of 0.99994 in the SP³ registers     

Digital canvas removal in paintings

The periodic structure of the underlying support of paintings on canvas can become quite prominent and disturbing in high resolution digital recordings. In this paper, we construct a new model and method for the digital removal of canvas which is considered as a noise component superimposed on the painting artwork. The high resolution of the images prohibits the efficient application of existing adaptive denoising filters. Hence, a two-step approach is proposed. First a (smoothing) Wiener filter is applied to the complete image. The second step consists of a spatially adaptive extension with low-complexity to obtain a generic digital canvas removal filter.     

Distributed call processing for personal communications services

The authors present a control architecture, procedures, and a signaling system to support advanced personal communication services (PCS). They describe the current cellular system architecture, and its algorithms and data management schemes for providing services. They present review how current cellular systems operate with a focus on mobility management and call and connection control. The benefits of this architecture include lower signaling traffic over wireless links, lower network load for signaling traffic, low call/connection delivery times, ubiquitous service offering, and more efficient routing of connections     

Some statistical properties of mathematical morphology

Analyzes the statistical properties of the basic binary and multilevel morphological operations with both 1-D and 2D structuring elements. Very simple expressions for the output distribution of erosion and opening are derived in the case of any independent identically or nonidentically distributed inputs. The probability relations between erosion and dilation, also between opening and closing, are developed. The output expectation bias and variances are analyzed and computed to show the efficiency of morphological operations for noise supression. As applications of theoretical results, the effects of the morphological operations on noisy signals are illustrated by several examples. The study reveals certain interesting phenomena. For example, the output variances of opening for some input distributions are greater than those of erosion, and morphological operations perform better than median filters in edge preservation     

Securing Scan Control in Crypto Chips

The design of secure ICs requires fulfilling means conforming to many design rules in order to protect access to secret data. On the other hand, designers of secure chips cannot neglect the testability of their chip since high quality production testing is primordial to a good level of security. However, security requirements may be in conflict with test needs and testability improvement techniques that increase both observability and controllability. In this paper, we propose to merge security and testability requirements in a control-oriented design for security scan technique. The proposed security scan design methodology induces an adaptation of two main aspects of testability technique design: protection at protocol level and at scan path level. Without loss of generality, the proposed solution is evaluated on a simple crypto chip in terms of security and design cost.

Design of an enhanced access point to optimize TCP performance in Wi-Fi hotspot networks

In the last years, the number of Wi-Fi hotspots at public venues has undergone a substantial growth, promoting the WLAN technologies as the ubiquitous solution to provide high-speed wireless connectivity in public areas. However, the adoption of a random access CSMA-based paradigm for the 802.11 MAC protocol makes difficult to ensure high throughput and a fair allocation of radio resources in 802.11-based WLANs. In this paper we evaluate extensively via simulations the interaction between the flow control mechanisms implemented at the TCP layer and the contention avoidance techniques used at the 802.11 MAC layer. We conducted our study considering initially M wireless stations performing downloads from the Internet. From our results, we observed that the TCP downlink throughput is not limited by the collision events, but by the inability of the MAC protocol to assign a higher chance of accessing the channel to the base station. We propose a simple and easy to implement modification of the base station’s behavior with the purpose of increasing the TCP throughput reducing useless MAC protocol overheads. With our scheme, the base station is allowed to transmit periodically bursts of data frames towards the mobile hosts. We design a resource allocation protocol aimed at maximizing the success probability of the uplink transmissions by dynamically adapting the burst length to the collision probability estimated by the base station. By its design, our scheme is also beneficial to achieve a fairer allocation of the channel bandwidth among the downlink and uplink flows, and among TCP and UDP flows. Simulation results confirm both the improvement in the TCP downlink throughput and the reduction of system unfairness.     

Construction of baselines for VoIP traffic management on open MANs

In the last century, owing to the constant evolution of technologies telecommunication networks have become increasingly robust, being able to support multiple services. These services are part of the heterogeneous network traffic that can be carried through the Internet. Many of these services, including VoIP, are latency sensitive. In other words, this means that their quality depends directly on the network quality of service. Since users tend to become more sensitive with the instability and unavailability of the network, it is important to improve traffic management. A particular type of data that could be used to improve VoIP traffic management is the Internet Protocol Detail Record (IPDR). IPDRs are tickets created by all VoIP call attempts which contain a group of information related to the call history. Because of its full range of information, IPDRs can be used to create VoIP traffic baselines. This paper presents the development of baselines based on IPDRs to support VoIP traffic management in open‐access Metropolitan Area Networks (MAN). Copyright © 2013 John Wiley & Sons, Ltd.