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1.
Software is the key technology in applications as diverse as accounting, hospital management, aviation, and nuclear power. Application advances in different domains such as these-each with different requirements-have propelled software development from small batch programs to large, real-time programs with multimedia capabilities. To cope, software's enabling technologies have undergone tremendous improvement in hardware, communications, operating systems, compilers, databases, programming languages, and user interfaces, among others. In turn, those improvements have fueled even more advanced applications. Improvements in VLSI technology and multimedia, for example, have resulted in faster, more compact computers that significantly widened the range of software applications. Database and user interface enhancements, on the other hand, have spawned more interactive and collaborative development environments. Such changes have a ripple effect on software development processes as well as on software techniques and tools. In this article, we highlight software development's crucial methods and techniques of the past 30 years 相似文献
2.
Ferroelectrically Gated Atomically Thin Transition‐Metal Dichalcogenides as Nonvolatile Memory 下载免费PDF全文
3.
Polyelectrolyte and silver nanoparticle modification of microfiltration membranes to mitigate organic and bacterial fouling 总被引:1,自引:0,他引:1
Diagne F Malaisamy R Boddie V Holbrook RD Eribo B Jones KL 《Environmental science & technology》2012,46(7):4025-4033
Membrane fouling remains one of the most problematic issues surrounding membrane use in water and wastewater treatment applications. Organic and biological fouling contribute to irreversible fouling and flux decline in these processes. The aim of this study was to reduce both organic and biological fouling by modifying the surface of commercially available poly(ether sulfone) (PES) membranes using the polyelectrolyte multilayer modification method with poly(styrenesulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDADMAC), and silver nanoparticles (nanoAg) integrated onto the surface as stable, thin (15 nm) films. PSS increases the hydrophilicity of the membrane and increases the negative surface charge, while integration of nanoAg into the top PSS layer imparts biocidal characteristics to the modified surface. Fouling was simulated by filtering aqueous solutions of humic acid (5 and 20 mg L(-1)), a suspension of Escherichia coli (10(6) colony-forming units (CFU) mL(-1)), and a mixture of both foulants through unmodified and modified PES membranes under batch conditions. Filtration and cleaning studies confirmed that the modification significantly reduced organic and biological fouling. 相似文献
4.
Madhu K. Shankarapani Subbu Ramamoorthy Ram S. Movva Srinivas Mukkamala 《Journal in Computer Virology》2011,7(2):107-119
One of the major problems concerning information assurance is malicious code. To evade detection, malware has also been encrypted
or obfuscated to produce variants that continue to plague properly defended and patched networks with zero day exploits. With
malware and malware authors using obfuscation techniques to generate automated polymorphic and metamorphic versions, anti-virus
software must always keep up with their samples and create a signature that can recognize the new variants. Creating a signature
for each variant in a timely fashion is a problem that anti-virus companies face all the time. In this paper we present detection
algorithms that can help the anti-virus community to ensure a variant of a known malware can still be detected without the
need of creating a signature; a similarity analysis (based on specific quantitative measures) is performed to produce a matrix
of similarity scores that can be utilized to determine the likelihood that a piece of code under inspection contains a particular
malware. Two general malware detection methods presented in this paper are: Static Analyzer for Vicious Executables (SAVE)
and Malware Examiner using Disassembled Code (MEDiC). MEDiC uses assembly calls for analysis and SAVE uses API calls (Static
API call sequence and Static API call set) for analysis. We show where Assembly can be superior to API calls in that it allows
a more detailed comparison of executables. API calls, on the other hand, can be superior to Assembly for its speed and its
smaller signature. Our two proposed techniques are implemented in SAVE) and MEDiC. We present experimental results that indicate
that both of our proposed techniques can provide a better detection performance against obfuscated malware. We also found
a few false positives, such as those programs that use network functions (e.g. PuTTY) and encrypted programs (no API calls
or assembly functions are found in the source code) when the thresholds are set 50% similarity measure. However, these false
positives can be minimized, for example by changing the threshold value to 70% that determines whether a program falls in
the malicious category or not. 相似文献
5.
Mechanical and thermal characterization of compression moulded polylactic acid natural fiber composites reinforced with hemp and lyocell fibers 下载免费PDF全文
This research evaluates the effects of PLA/PP blend ratio and Lyocell/hemp mixture ratio on the morphology, water absorption, mechanical and thermal properties of PLA‐based composites. The composites were fabricated with 30 mass % hemp using compression moulding. As a reference composites made from PP were also studied. Combining of hemp and Lyocell in PLA composite leads to the reduction of moisture absorption and can improve the impact, tensile, flexural properties when compared with PLA/hemp. Composite based on the PLA/PP blend‐matrix could not improve the tensile and flexural properties compared with PLA/hemp, however; the lighter composite with better impact properties was obtained. The crystallization temperature of the PLA‐PP/hemp increased compared with pure PLA. This result was also confirmed by the SEM micrographs. The moisture absorption of PLA‐PP/hemp was higher than PLA/hemp. Based on theoretical analysis of DMTA data, there was favorable adhesion in all composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40534. 相似文献
6.
Polking MJ Han MG Yourdkhani A Petkov V Kisielowski CF Volkov VV Zhu Y Caruntu G Alivisatos AP Ramesh R 《Nature materials》2012,11(8):700-709
Ferroelectricity in finite-dimensional systems continues to arouse interest, motivated by predictions of vortex polarization states and the utility of ferroelectric nanomaterials in memory devices, actuators and other applications. Critical to these areas of research are the nanoscale polarization structure and scaling limit of ferroelectric order, which are determined here in individual nanocrystals comprising a single ferroelectric domain. Maps of ferroelectric structural distortions obtained from aberration-corrected transmission electron microscopy, combined with holographic polarization imaging, indicate the persistence of a linearly ordered and monodomain polarization state at nanometre dimensions. Room-temperature polarization switching is demonstrated down to ~5?nm dimensions. Ferroelectric coherence is facilitated in part by control of particle morphology, which along with electrostatic boundary conditions is found to determine the spatial extent of cooperative ferroelectric distortions. This work points the way to multi-Tbit/in(2) memories and provides a glimpse of the structural and electrical manifestations of ferroelectricity down to its ultimate limits. 相似文献
7.
Investigation and optimization of lubrication parameters in high speed turning of superalloy Inconel 718 总被引:2,自引:2,他引:0
Dinesh G. Thakur B. Ramamoorthy L. Vijayaraghavan 《The International Journal of Advanced Manufacturing Technology》2010,50(5-8):471-478
Dry machining is sometimes less effective when higher machining efficiency, better surface finish quality, and severe cutting conditions are required. For these situations, semi-dry operations utilizing very small amount of cutting fluids called minimum quantity lubrication is expected to become a powerful tool and played a significant role in a number of practical applications. It has been observed from the literature survey that a systematic research work has to be carried out to determine the optimum quantity of lubricant with appropriate cutting conditions for achieving better machinability characteristics of a material. Hence, an attempt has been made in this paper to enhance the machinability characteristics in high speed turning of superalloy Inconel 718 using quantity of lubricant, delivery pressure at the nozzle, frequency of pulses, direction of application of cutting fluid, cutting speed, and feed rate as the process parameters. Results indicated that the use of optimized minimum quantity lubrication parameters under pulsed jet mode leads to lower cutting force, cutting temperature, and flank wear. 相似文献
8.
A high conversion light water reactor lattice has been analysed using the code DRAGON Version4. This analysis was performed to test the performance of the advanced self-shielding models incorporated in DRAGON Version4. The self-shielding models are broadly classified into two groups – “equivalence in dilution” and “subgroup approach”. Under the “equivalence in dilution” approach we have analysed the generalized Stamm’ler model with and without Nordheim model and Riemann integration. These models have been analysed also using the Livolant–Jeanpierre normalization. Under the “subgroup approach”, we have analysed Statistical self-shielding model based on physical probability tables and Ribon extended self-shielding model based on mathematical probability tables. This analysis will help in understanding the performance of advanced self-shielding models for a lattice that is tight and has a large fraction of fissions happening in the resonance region. The nuclear data for the analysis was generated in-house. NJOY99.90 was used for generating libraries in DRAGLIB format for analysis using DRAGON and A Compact ENDF libraries for analysis using MCNP5. The evaluated datafiles were chosen based on the recommendations of the IAEA Co-ordinated Research Project on the WIMS Library Update Project. The reference solution for the problem was obtained using Monte Carlo code MCNP5. It was found that the Ribon extended self-shielding model based on mathematical probability tables using correlation model performed better than all other models. 相似文献
9.
Chen Y.-F. Nishimoto M.Y. Ramamoorthy C.V. 《IEEE transactions on pattern analysis and machine intelligence》1990,16(3):325-334
A system for analyzing program structures is described. The system extracts relational information from C programs according to a conceptual model and stores the information in a database. It is shown how several interesting software tasks can be performed by using the relational views. These tasks include generation of graphical views, subsystem extraction, program layering, dead code elimination and binding analysis 相似文献
10.
On the capacity of network coding for random networks 总被引:1,自引:0,他引:1
Ramamoorthy A. Shi J. Wesel R.D. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2005,51(8):2878-2885
We study the maximum flow possible between a single-source and multiple terminals in a weighted random graph (modeling a wired network) and a weighted random geometric graph (modeling an ad-hoc wireless network) using network coding. For the weighted random graph model, we show that the network coding capacity concentrates around the expected number of nearest neighbors of the source and the terminals. Specifically, for a network with a single source, l terminals, and n relay nodes such that the link capacities between any two nodes is independent and identically distributed (i.i.d.) /spl sim/X, the maximum flow between the source and the terminals is approximately nE[X] with high probability. For the weighted random geometric graph model where two nodes are connected if they are within a certain distance of each other we show that with high probability the network coding capacity is greater than or equal to the expected number of nearest neighbors of the node with the least coverage area. 相似文献