Effect of substrate biasing and temperature on AlN thin film deposited by cathodic arc ion

Aluminum nitride (AlN) films have been grown in pure N₂ plasma using cathodic arc ion deposition process. The films were prepared at different substrate bias voltages and temperatures. The aim was to investigate their influence on the Al macro-particles, structural and optical properties of deposited films. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning electron microscope (SEM) and Rutherford backscattering spectrometry (RBS) were employed to characterize AlN thin films. XRD patterns indicated the formation of polycrystalline (hexagonal) films with preferential orientation of (002), which is suppressed at higher substrate bias voltage. FTIR and Raman spectroscopic analysis were used to assess the nature of chemical bonding and vibrational phonon modes of AlN thin films respectively. FTIR spectra depicted a dominant peak around 850 cm^?1 corresponding to the longitudinal optical (LO) mode of vibration. A shift in this LO mode peak towards higher wavenumbers was observed with the increase of substrate bias voltage and temperature, showing the upsurge of nitrogen concentration in the deposited film. Raman spectra illustrated a peak at 650 cm^?1 corresponding to E₂ (high) phonon mode depicting the c-axis oriented (perpendicular to substrate) AlN film. SEM analysis showed the AlN film deposited at higher substrate bias voltage contains fewer amounts of Al macro-particles.     

Thermal and mechanical properties of SEBS-g-MA based inorganic composite materials

Organic-inorganic hybrids based on a triblock copolymer [polystyrene-b-poly (ethylene-ran-butylene)-b-polystyrene-g-maleic anhydride] (SEBS-g-MA) with silica and clay were prepared using sol-gel and solution intercalation methods respectively. Reinforcement in the first system was achieved by the in-situ hydrolysis/condensation of tetraethoxysilane in the copolymer matrix yielding hybrid materials. The interaction between organic and inorganic phases was developed through a coupling agent. In another system, copolymer was reinforced by organoclay and compatibility between copolymer and hydrophilic montmorillonite was achieved by intercalation of clay with dodecylamine which increased the organophilicity of the clay. Thin transparent films of these hybrids materials were characterized for their mechanical, thermal and thermomechanical behavior. The tensile strength of hybrids improved relative to the pure copolymer in all the systems. Dynamic mechanical thermal analysis carried out gave α-relaxation temperature associated with glass transition temperature (T_g). The results indicate a shift in T_g values with the addition of silica in the matrix, which suggests an increased interfacial interaction between organic and inorganic phases while this effect is less pronounced in polymer–clay system. Thermal decomposition temperatures of the hybrids were found in the range of 450–500 °C. The weights of the residues left at 700 °C were nearly proportional to the inorganic contents in the original hybrids.     

Optimization of core reload pattern for PARR-1 using evolutionary techniques

A procedure for searching optimum loading pattern to ensure safe and efficient reactor utilization was established for Pakistan Research Reactor-1 (PARR-1). A 6 × 5 core of PARR-1 consisting of 24 standard fuel elements, 5 control fuel elements and one flux trap was used in the study. The optimum loading schemes for maximum cycle length and maximum thermal flux in the flux trap were recommended using the developed methodology.     

A Novel Approach for Security Enhancement of Data Encryption Standard

Data Encryption Standard (DES) is a symmetric key cryptosystem that is applied in different cryptosystems of recent times. However, researchers found defects in the main assembling of the DES and declared it insecure against linear and differential cryptanalysis. In this paper, we have studied the faults and made improvements in their internal structure and get the new algorithm for Improved DES. The improvement is being made in the substitution step, which is the only nonlinear component of the algorithm. This alteration provided us with great outcomes and increase the strength of DES. Accordingly, a novel good quality S-box construction scheme has been hired in the substitution phase of the DES. The construction involves the Galois field method and generates robust S-boxes that are used to secure the scheme against linear and differential attacks. Then again, the key space of the improved DES has been enhanced against the brute force attack. The outcomes of different performance analyses depict the strength of our proposed substitution boxes which also guarantees the strength of the overall DES.     

Modeling robustness behavior using aspect-oriented modeling to support robustness testing of industrial systems

Model-based robustness testing requires precise and complete behavioral, robustness modeling. For example, state machines can be used to model software behavior when hardware (e.g., sensors) breaks down and be fed to a tool to automate test case generation. But robustness behavior is a crosscutting behavior and, if modeled directly, often results in large, complex state machines. These in practice tend to be error prone and difficult to read and understand. As a result, modeling robustness behavior in this way is not scalable for complex industrial systems. To overcome these problems, aspect-oriented modeling (AOM) can be employed to model robustness behavior as aspects in the form of state machines specifically designed to model robustness behavior. In this paper, we present a RobUstness Modeling Methodology (RUMM) that allows modeling robustness behavior as aspects. Our goal is to have a complete and practical methodology that covers all features of state machines and aspect concepts necessary for model-based robustness testing. At the core of RUMM is a UML profile (AspectSM) that allows modeling UML state machine aspects as UML state machines (aspect state machines). Such an approach, relying on a standard and using the target notation as the basis to model the aspects themselves, is expected to make the practical adoption of aspect modeling easier in industrial contexts. We have used AspectSM to model the crosscutting robustness behavior of a videoconferencing system and discuss the benefits of doing so in terms of reduced modeling effort and improved readability.     

Zen-ReqOptimizer: a search-based approach for requirements assignment optimization

At early phases of a product development lifecycle of large scale Cyber-Physical Systems (CPSs), a large number of requirements need to be assigned to stakeholders from different organizations or departments of the same organization for review, clarification and checking their conformance to standards and regulations. These requirements have various characteristics such as extents of importance to the organization, complexity, and dependencies between each other, thereby requiring different effort (workload) to review and clarify. While working with our industrial partners in the domain of CPSs, we discovered an optimization problem, where an optimal solution is required for assigning requirements to various stakeholders by maximizing their familiarity to assigned requirements, meanwhile balancing the overall workload of each stakeholder. In this direction, we propose a fitness function that takes into account all the above-mentioned factors to guide a search algorithm to find an optimal solution. As a pilot experiment, we first investigated four commonly applied search algorithms (i.e., GA, (1 + 1) EA, AVM, RS) together with the proposed fitness function and results show that (1 + 1) EA performs significantly better than the other algorithms. Since our optimization problem is multi-objective, we further empirically evaluated the performance of the fitness function with six multi-objective search algorithms (CellDE, MOCell, NSGA-II, PAES, SMPSO, SPEA2) together with (1 + 1) EA (the best in the pilot study) and RS (as the baseline) in terms of finding an optimal solution using an real-world case study and 120 artificial problems of varying complexity. Results show that both for the real-world case study and the artificial problems (1 + 1) EA achieved the best performance for each single objective and NSGA-II achieved the best performance for the overall fitness. NSGA-II has the ability to solve a wide range of problems without having their performance degraded significantly and (1 + 1) EA is not fit for problems with less than 250 requirements Therefore we recommend that, if a project manager is interested in a particular objective then (1 + 1) EA should be used; otherwise, NSGA-II should be applied to obtain optimal solutions when putting the overall fitness as the first priority.     

Cotton fabric dyeability assessment of floral extracts obtained from binary mixtures of Callistemon citrinus and Tagetes erecta L

Parameters affecting extraction of natural colorants from five binary mixtures of floral parts of Callistemon citrinus and Tagetes erecta L., like ratio of each flower in the binary mixture of powdered floral parts, amount of powdered binary mixture to liquor ratio and extraction time, were optimized for dyeing of cotton fabric. Optimum dyeing was obtained at 60°C with 70 g/L exhausting agent (Na₂SO₄), material to liquor ratio of 1:50 along with dyeing time of 100 min. The dyed fabric revealed good anti-bacterial activity and excellent ultraviolet protection factor (UPF).     

Philosophy of water reuse in Islamic perspective

A large number of Muslim countries have arid climate and face severe shortage of fresh water supplies for their development programs. It makes it imperative to utilize each drop of reusable water after proper treatment. The Qur'an, while emphasizing the importance of water as such, and its functions as an agent for purification, does not spell out specific rules regarding the reuse of waste water effluents. A number of sayings and actions of the Prophet Muhammed (peace be upon him) about water are, however, found in the Traditions of the Prophet (called Hadith). Consistent with the general approach of Islam to human problems, which is characterized by practicality and concern for ease in human life, the teachings embodied in the Hadith on this question are of a liberal nature. In the traditional legal literature of Islam, there exists the concept of unclean and used water being made a part of the over-all supply of clean water and being used thereafter. To make use of modern technology in order to recycle waste water effluents after treatment seems quite in keeping with the spirit and letter of the Islamic teachings, though of course considerations of health, cost and public acceptance are always bound to be taken into consideration.     

Material properties of ZnS nanoparticles incorporated soy protein isolate biopolymeric film

ABSTRACT

Glycerol plasticised soy protein isolate (SPI) films at different contents (1 to 5% w/w w.r.t SPI) of zinc sulphide (ZnS) nanoparticles were fabricated. Before the film formation, the ZnS nanoparticles incorporated SPI suspensions were subjected to molecular mass studies by SDS-PAGE and specific conductivity studies. SPI films and ZnS nanoparticles incorporated SPI films were structurally and mechanically characterised by Fourier transform infrared spectroscopy (FT-IR) and mechanical properties, respectively. Transmittance and water uptake studies were also carried out for ZnS nanoparticles incorporated SPI films. The results from transmittance, water uptake and FT-IR studies indicated a good compatibility between the ZnS nanoparticles and the SPI. With the increase in the contents of ZnS nanoparticles from 0 to 4%, the tensile modulus increased from 87.4 to 99?MPa. The water uptake decreased significantly from 159 to 10.76%. However, the results showed the absence of antibacterial effect in ZnS nanoparticles incorporated SPI film.     

Free Vibration of Laminated Composite Shallow Shells Containing Piezoelectric Layers

The free vibration of laminated shallow shells containing piezoelectric layers is investigated in this article. A finite-element formulation based on the transverse shear deformation theory has been used to determine the natural frequencies, mode shapes, and modal voltages of laminated composite shell structures containing piezoelectric layers. Comparisons of degenerate cases with published results show excellent agreement. The effect of electromechanical coupling on the predicted natural frequencies is discussed. Results are presented for different geometries, laminate configurations, and boundary conditions. The effects of shell shallowness and piezoelectric layer thickness are also studied. Higher natural frequencies are obtained when the full electromechanical coupling is considered. It is also found that the natural frequencies increase considerably with the shell curvature, particularly for thin piezoelectric layers.