Practical Equivalent Continuum Model for Simulation of Jointed Rock Mass Using FLAC3D

A simple practical equivalent continuum numerical model for simulating the behavior of jointed rock mass has been extended to three-dimensional using FLAC3D. This model estimates the properties of jointed rock mass from the properties of intact rock and a joint factor (Jf), which is the integration of the properties of joints to take care of the effects of frequency, orientation, and strength of joint. A new FISH function has been written in FLAC3D specifically for modeling jointed rocks using the Duncan and Chang hyperbolic model. This model has been validated first with simple element tests at different confining pressures for different rocks with different joint configurations. Explicit modeling of the joints has also been done in element tests and results obtained compare well with the results of equivalent continuum model and also with experimental results. Further, this has been applied for a case study of a large underground power house cavern in the Himalayas. The analysis has been done under various stages of excavation, assigning a null model available in FLAC3D for simulating the excavation.     

Binary rewriting and call interception for efficient runtime protection against buffer overflows

Buffer overflow vulnerabilities are one of the most commonly and widely exploited security vulnerabilities in programs. Most existing solutions for avoiding buffer overflows are either inadequate, inefficient or incompatible with existing code. In this paper, we present a novel approach for transparent and efficient runtime protection against buffer overflows. The approach is implemented by two tools: Type Information Extractor and Depositor (TIED) and LibsafePlus. TIED is first used on a binary executable or shared library file to extract type information from the debugging information inserted in the file by the compiler and reinsert it in the file as a data structure available at runtime. LibsafePlus is a shared library that is preloaded when the program is run. LibsafePlus intercepts unsafe C library calls such as strcpy and uses the type information made available by TIED at runtime to determine whether it would be ‘safe’ to carry out the operation. With our simple design we are able to protect most applications with a performance overhead of less than 10%. Copyright © 2006 John Wiley & Sons, Ltd.     

The design,analysis, and cost estimation of a generic adder and subtractor using the layered T (LT) logic reduction methodology with a quantum-dot cellular-automata-based approach

The quantum-dot cellular automata (QCA) is considered to be one of the ground-breaking nanotechnologies developed over the last two decades. A layered T (LT) logic cell library is constructed herein, and the methodology is extended to generic adder and subtractor module designs. The two proposed algorithms lead to more efficient QCA layout designs for an n-bit ripple carry adder (RCA) and subtractor based on an effective clock zone assignment approach. The suggested one-, four-, and eight-bit RCAs and subtractors surpass most of their existing counterparts by offering lower effective area and cell complexity. A comparative analysis is presented regarding the complexity, irreversible power dissipation, and Cost_α of the proposed n-bit layouts from a cost estimation purview.

     

Improvement of polymer blend properties by changing sequence of mixing

The basic objective of this article is to improve the polymer blend properties by changing mixing sequence. Blending of two elastomers does not lead to a molecularly homogeneous blend (true solution), but to a heterogeneous system in which both polymer phases are present. In this article, the detailed study of heterogeneous distribution of carbon black as well as blend inhomogenity and the physicomechanical including dynamic mechanical properties of the blend has been carried out. The choice of the blend was natural rubber/polybutadiene rubber as 85:15. Heterogeneous carbon black distribution study was also performed in differential scanning calorimeter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2735–2742, 2007     

Part and Attribute Discovery from Relative Annotations

Part and attribute based representations are widely used to support high-level search and retrieval applications. However, learning computer vision models for automatically extracting these from images requires significant effort in the form of part and attribute labels and annotations. We propose an annotation framework based on comparisons between pairs of instances within a set, which aims to reduce the overhead in manually specifying the set of part and attribute labels. Our comparisons are based on intuitive properties such as correspondences and differences, which are applicable to a wide range of categories. Moreover, they require few category specific instructions and lead to simple annotation interfaces compared to traditional approaches. On a number of visual categories we show that our framework can use noisy annotations collected via “crowdsourcing” to discover semantic parts useful for detection and parsing, as well as attributes suitable for fine-grained recognition.     

A new fuzzy rule based algorithm for estimating software faults in early phase of development

Estimation of reliability and the number of faults present in software in its early development phase, i.e., requirement analysis or design phase is very beneficial for developing reliable software with optimal cost. Software reliability prediction in early phase of development is highly desirable to the stake holders, software developers, managers and end users. Since, the failure data are unavailable in early phase of software development, different reliability relevant software metrics and similar project data are used to develop models for early software fault prediction. The proposed model uses the linguistic values of software metrics in fuzzy inference system to predict the total number of faults present in software in its requirement analysis phase. Considering specific target reliability, weightage of each input software metrics and size of software, an algorithm has been proposed here for developing general fuzzy rule base. For model validation of the proposed model, 20 real software project data have been used here. The linguistic values from four software metrics related to requirement analysis phase have been considered as model inputs. The performance of the proposed model has been compared with two existing early software fault prediction models.     

Measurement Uncertainty in Airborne Sound Insulation and Single-Number Quantities: Strategy and Implementation in Indian Scenario

This paper presents the factors affecting the uncertainty of measurement in sound transmission loss testing and the single-number quantities (SNQs) used widely in building acoustics. It provides a retrospective view of the recently published work especially in European continent and standard ISO 12999-1 for interpreting and elaborating the concept of calculation of measurement uncertainty in SNQs particularly for the laboratories engaged in sound transmission loss testing in India by presenting case studies for different types of building materials. The study suggests that the poor low frequency sound insulation and low frequency mass-air-mass and flexural resonances inculcate a higher uncertainty in SNQs for building elements. It is imperative to adopt the strategy recommended in ISO 12999-1 in Indian scenario particularly with growing international trade in building materials and technology and for the recognition as well as acceptance of testing results of Indian laboratories across the globe.     

发动机气道CFD分析流程自动化研究

在成熟的发动机气道CFD分析流程的基础上,基于CFD分析软件Star-ccm+和Java编程语言,提出并探索了发动机气道CFD分析流程自动化的解决方案,并开发出了简单的气道CFD自动化分析平台,可在一定程度上提高气道CFD分析的效率.该方案对其他CFD分析问题的流程自动化也具有借鉴意义.     

Surface Actuation of Lightweight Mirrors with Shape Memory Alloy

The ability to create lightweight mirrors that can maintain surface accuracy is a major technical challenge for future space telescopes. Processing-induced errors and surface errors due to temperature excursions and gravity sag (zero gravity in space) make it impossible to correct the surface of thin mirror face-sheets by conventional point actuators. The challenges are compounded by the requirements for mirrors to have adequate stiffness for pointing accuracy. An experimental and analytical study was conducted to explore the feasibility of correcting the shape of lightweight (≈1 kg/m2) mirrors using a “Nitinol” (nickel-titanium) shape memory alloy (SMA). Shape memory alloys are increasingly used as smart devices in aerospace applications. Their primary advantage over other smart materials (i.e., piezo-ceramics and piezo-polymers) is in their ability to undergo large strains and displacements and thus enable the development of smart mechanisms. Active shape correction is the only means of mitigating heat and zero-gravity-induced distortions in space-based optical imaging systems. The repeatability and reliability of a possible actuation system based on properties of the SMA wires were studied by testing the stress-strain and stress recovery behavior under controlled conditions. Embedded SMA wires were then used to actuate a composite beam, and the movement induced by actuation was monitored with the Moiré interferometry method.