A pointer logic and certifying compiler

Proof-Carrying Code brings two big challenges to the research field of programming languages. One is to seek more expressive logics or type systems to specify or reason about the properties of low-level or high-level programs. The other is to study the technology of certifying compilation in which the compiler generates proofs for programs with annotations. This paper presents our progress in the above two aspects. A pointer logic was designed for PointerC (a C-like programming language) in our research. As an extension of Hoare logic, our pointer logic expresses the change of pointer information for each statement in its inference rules to support program verification. Meanwhile, based on the ideas from CAP (Certified Assembly Programming) and SCAP (Stack-based Certified Assembly Programming), a reasoning framework was built to verify the properties of object code in a Hoare style. And a certifying compiler prototype for PointerC was implemented based on this framework. The main contribution of this paper is the design of the pointer logic and the implementation of the certifying compiler prototype. In our certifying compiler, the source language contains rich pointer types and operations and also supports dynamic storage allocation and deallocation.     

Verhalten geschweißter Magnesiumlegierungen unter mechanisch‐korrosiver Komplexbeanspruchung

Corrosion and corrosion fatigue of welded magnesium alloys In addition to the prevalent use of magnesium cast alloys a high potential for lightweight constructions is offered by magnesium‐wrought alloys, in particular in the automobile industry. The use of rolled and/or extruded magnesium alloys (profiles and sheet metals) requires suitable and economic join technologies like different welding procedures in order to join semi finished parts. Thus, the realization of lightweight constructions asks for high standards of materials‐ and joining‐technologies. In this context, the mechanical properties as well as the corrosion behaviour of the joints are of large interest. During welding of magnesium alloys, influences concerning the surface, the internal stresses and the microstructure occur. These influences particularly depend on the energy input and thus, on the welding procedure as well as the processing parameters, which all affect the corrosion behaviour of the joints. Sheets of magnesium alloys (AZ31, AZ61, AZ91) were joined with different welding procedures (plasma‐, laser beam‐ and electron‐beam welding in the vacuum and at atmosphere). The corrosion behaviour (with and without cyclic mechanical loading) of the welded joints was investigated by different methods such as corrosion tests, polarisation curves, scanning electron microscopy and metallography. Furthermore, substantial influencing variables on the corrosion behaviour of welded joints of magnesium alloys are pointed out and measures are presented, which contribute to the improvement of the corrosion behaviour.     

信息家电接口定义语言(IAIDL)的研究

分析了在信息家电体系结构中引入信息家电接口定义语言的必要性和意义,明确地给出了IAIDL语言的定位,并根据这个定位制订了IAIDL的语法规范,最后还就它的完备性给出了证明.     

基于分散内存式多处理器系统的延迟判断式投机执行并行处理方式的提案

针对并行计算机进行并行处理时条件分支会影响程序并行性的问题，提出了一种基于分散内存系统的延迟判断式投机执行并行处理方式。这种并行处理方式有处理时间（overhead）短，对硬件依赖性小等优点。     

Efficient embedded code generation with multiple load/store instructions

In a recent study, we discovered that many single load/store operations in embedded applications can be parallelized and thus encoded simultaneously in a single‐instruction multiple‐data instruction, called the multiple load/store (MLS) instruction. In this work, we investigate the problem of utilizing MLS instructions to produce optimized machine code, and propose an effective approach to the problem. Specifically, we formalize the MLS problem, that is, the problem of maximizing the use of MLS instructions with an unlimited register file size. Based on this analysis, we show that we can solve the problem efficiently by translating it into a variant of the problem finding a maximum weighted path cover in a dynamic weighted graph. To handle a more realistic case of the finite size of the register file, our solution is then extended to take into account the constraints of register sequencing in MLS instructions and the limited register resource available in the target processor. We demonstrate the effectiveness of our approach experimentally by using a set of benchmark programs. In summary, our approach can reduce the number of loads/stores by 13.3% on average, compared with the code generated from existing compilers. The total code size reduction is 3.6%. This code size reduction comes at almost no cost because the overall increase in compilation time as a result of our technique remains quite minimal. Copyright © 2007 John Wiley & Sons, Ltd.     

基于VC++和MATLAB混合编程绘制三维图形

文章介绍了VC 环境下调用MATLAB实现绘制三维图形的两种方法:利用MATLAB编译器和MATLAB引擎,并用实例证明这两种方法可实现VC 的用户界面与MATLAB的强大图形功能的交互.分析了这两种方法的优缺点,对各自的接口环境配置进行了对比,详细说明了两种方法的具体步骤,提出了各自适合的应用时机.     

Compile-time copy elimination

Single-assignment and functional languages have value semantics that do not permit side-effects. This lack of side-effects makes automatic detection of parallelism and optimization for data locality in programs much easier. However, the same property poses a challenge in implementing these languages efficiently. This paper describes an optimizing compiler system that solves the key problem of aggregate copy elimination. The methods developed rely exclusively on compile-time algorithms, including interprocedural analysis, that are applied to an intermediate data flow representation. By dividing the problem into update-in-place and build-in-place analysis, a small set of relatively simple techniques—edge substitution, graph pattern matching, substructure sharing and substructure targeting—was found to be very powerful. If combined properly and implemented carefully, the algorithms eliminate unnecessary copy operations to a very high degree. No run-time overhead is imposed on the compiled programs.     

Fast and accurate fuzzy C‐means algorithm for MR brain image segmentation

Fuzzy theory based intelligent techniques are widely preferred for medical applications because of high accuracy. Among the fuzzy based techniques, Fuzzy C‐Means (FCM) algorithm is popular than the other approaches due to the availability of expert knowledge. But, one of the hidden facts is that the computational complexity of the FCM algorithm is significantly high. Since medical applications need to be time effective, suitable modifications must be made in this algorithm for practical feasibility. In this study, necessary changes are included in the FCM approach to make the approach time effective without compromising the segmentation efficiency. An additional data reduction approach is performed in the conventional FCM to minimize the computational complexity and the convergence rate. A comparative analysis with the conventional FCM algorithm and the proposed Fast and Accurate FCM (FAFCM) is also given to show the superior nature of the proposed approach. These techniques are analyzed in terms of segmentation efficiency and convergence rate. Experimental results show promising results for the proposed approach. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 188–195, 2016