Hyper-Kloosterman Sums and their Applications to the Coding Theory

The dual code of the Melas code is called the Kloosterman code. The weights of its codewords can be expressed by the Kloosterman sums, and are uniformly distributed with respect to the Sato-Tate measure. In this paper, the hyper-Kloosterman code C _m (q), a generalization of the Kloosterman code is defined, and the uniform distribution property is deduced using the hyper-Kloosterman sums when m is even and p− 1|m. Finally we discuss doubly-evenness for the weights in the binary case. It shows that we can construct infinitely many doubly-even codes in a non-trivial way. Received: October 30, 2000; revised version: February 28, 2001     

Modeled salt density for nuclear material estimation in the treatment of spent nuclear fuel

Spent metallic nuclear fuel is being treated in a pyrometallurgical process that includes electrorefining the uranium metal in molten eutectic LiCl-KCl as the supporting electrolyte. We report a model for determining the density of the molten salt. Material balances account for the net mass of salt and for the mass of actinides present. It was necessary to know the molten salt density, but difficult to measure. It was also decided to model the salt density for the initial treatment operations. The model assumes that volumes are additive for the ideal molten salt solution as a starting point; subsequently, a correction factor for the lanthanides and actinides was developed. After applying the correction factor, the percent difference between the net salt mass in the electrorefiner and the resulting modeled salt mass decreased from more than 4.0% to approximately 0.1%. As a result, there is no need to measure the salt density at 500 °C for inventory operations; the model for the salt density is found to be accurate.     

MIMO Frequency Hopping Spread Spectrum Multi-Carrier Multiple Access: A Novel Uplink System for B3G Cellular Networks

In this paper, we propose and give the performance of a novel uplink system based on the combination of multi-carrier (MC), code division multiple access (CDMA) and multiple input multiple output (MIMO) techniques. First, we describe the interests of spread-spectrum multi-carrier multiple access (SS-MC-MA) scheme for uplink, especially compared to MC-CDMA. Classically, with SS-MC-MA, each user spreads its data symbols on a specific subset of adjacent or multiplexed subcarriers, to facilitate the channel estimation and reduce complexity at the reception. In order to compensate for the lack of frequency diversity of SS-MC-MA with adjacent subcarriers, we first combine it with an orthogonal space-time block code (STBC) and demonstrate the resulting spatial diversity gain. Then, we propose to allocate the subsets to the different users by applying a frequency hopping pattern (FH). In that case, each user benefits from the frequency diversity linked to the total bandwidth as with the multiplexed subcarriers solution, while keeping the advantages of the adjacent subcarriers solution. The gain provided by the use of the frequency hopping is stressed on. Finally, the performance of this scheme is evaluated over realistic MIMO channel with channel turbo coding for systems offering asymptotic spectrum efficiency of 1, 2, 3 and 4.5 bit/s/Hz. Thus, the efficiency of the novel proposed STBC FH SS-MC-MA system as a very promising multiple access and modulation scheme for the uplink of the future wideband wireless networks is successfully demonstrated.     

光通信系统中数字配线架电接触不良的影响

基于现场搜集的连接器，分析了可能导致电接触不良的因素，并且根据电接触理论结合高频传输的特点建立了通信系统中电触点的物理模型。最后以光通信系统中数字配线架（ＤＤＦ）上的同轴连接器为例，探讨了电触点故障导致误码率增高的可能性。     

用软件实现回溯方式的维特比译码

本文在分析维特比译码原理的基础上，提出了用软件编程实现回溯方式的维特比译码的设计和处理技巧。     

键位分布合理指数与动态平均码长综合指标的自动测定

本文引进速度码长概念作为测定汉字键盘输入系统速度素质的客观指标, 以解决当前汉字字、词输入、软件智能处理的输入系统对评佑技术提出的新课题。对速度素质的计算机自动测定摆脱了由操作员作竞赛性测定人为素质的干扰,为汉字键盘输入评测提出新的理论依据和提供了测试软件。     

A new parallel algorithm for parsing arithmetic infix expressions

A new parallel algorithm for transforming an arithmetic infix expression into a par se tree is presented. The technique is based on a result due to Fischer (1980) which enables the construction of the parse tree, by appropriately scanning the vector of precedence values associated with the elements of the expression. The algorithm presented here is suitable for execution on a shared memory model of an SIMD machine with no read/write conflicts permitted. It uses O(n) processors and has a time complexity of O(log²n) where n is the expression length. Parallel algorithms for generating code for an SIMD machine are also presented.     

汉明码编译码的FPGA设计与实现

利用ALTERA公司的FLEX10K系列芯片设计和实现了汉明码的编译码,详细地阐述了设计的方法和实现的过程。首先进行电路设计,然后在MAX PLUSII编辑环境下,采用自顶向下的层次设计方法,以及VHDL文本输入的输入方法编制程序,经编译正确后进行波形仿真,经过仿真、调试,验证了功能和时序正确性后,将编辑的程序烧写到FPGA。     

‘Baltimore does not condone profiteering in squalor’: the Baltimore Plan and the problem of housing-code enforcement in an American city

In 1941, the Baltimore City Council passed a law, the Ordinance on the Hygiene of Housing, declaring that all property in the city should be ‘maintained in good repair by the owner or agent, and fit for human habitation’. The campaign of housing-code enforcement that followed, known as the Baltimore Plan, made the city famous. When historians write about American housing-reform efforts during the mid-20th century, they tend to focus on big-ticket federal policies; by contrast, the Baltimore Plan seems too small to be significant. But it is more than a curiosity. First in Baltimore and then across the country, the neat cause-and-effect it posited between good stewardship and good housing crowded out more challenging ways of thinking about the problem. Eventually, the Baltimore Plan turned into a policy tool that reinforced the interests of the real estate industry at the expense of poor people. In that regard, the Baltimore Plan laid the foundations for federal disinvestment in the provision of decent housing and the midcentury tragedy of urban renewal.     

Methodology for development of live load models for refined analysis of short and medium-span highway bridges

Abstract

The accuracy of bridge system safety evaluations and reliability assessments obtained through refined structural and finite element analyses depends not only on the accuracy of the structural model itself but also on the proper modelling of the maximum traffic loads. While current code-specified live load models were calibrated to properly reflect the safety levels of bridge structures analysed using the simplified methods adopted in bridge design and evaluation manuals, these load models may not lead to accurate results when implemented during refined structural analysis procedures. This paper describes a method to calibrate appropriate live load models that can be used for advanced analyses of bridges. The calibration procedure is demonstrated using actual traffic data collected at a representative weigh-in-motion station in New York State. The proposed calibration methodology is applicable for developing live load models for different bridge service periods, bridge types and design/assessment codes or standards. Live load models obtained using the proposed calibration procedure are readily implementable for deterministic refined analyses of highway bridges to produce similar results to those of complex traffic load simulations. Examples are presented that describe how results of such calibrated live load models would be used in engineering practice.