Determination of material removal rate in wire electro-discharge machining of metal matrix composites using dimensional analysis

Wire electro-discharge machining (WEDM) is a vital process in manufacturing intricate shapes. The present work proposes a semi-empirical model for material removal rate in WEDM based on thermo-physical properties of the work piece and machining parameters such as pulse on-time and average gap voltage. The model is developed by using dimensional analysis and non-linear estimation technique such as quasi-Newton and simplex. Predictability of the proposed model is more than 99% for all work materials studied. The work materials were silicon carbide particulate reinforced aluminium matrix composites. The experiments and model prediction show significant role of coefficient of thermal expansion in WEDM of these materials. In addition, an empirical model, based on response surface method, has also been developed. The comparison of these models shows significant agreement in the predictions.     

LOCA frequency evaluation using expert elicitation

The double-ended-guillotine break (DEGB) criterion of the largest primary piping system in the plant, which generally provides the limiting condition for the emergency core cooling system requirements, is widely recognized as an extremely unlikely event. As a result, US Nuclear Regulatory Commission (NRC) staff are currently considering a risk-informed revision of the design-basis break size requirements for commercial nuclear power plants. In support of this effort, loss-of-coolant accident (LOCA) frequency estimates have been developed using an expert elicitation process by consolidating service history data and insights from probabilistic fracture mechanics (PFM) studies with knowledge of plant design, operation, and material performance. Baseline LOCA frequency estimates for the 5th percentile, median, mean and 95th percentile were determined from each panelist's elicitation responses. Group estimates were determined by aggregating the individual estimates using the geometric mean of the individual estimates for each frequency parameter. Group variability was estimated by calculating 95% confidence bounds for each of the group frequency parameters (i.e., median, mean, and 5th and 95th percentiles). A number of sensitivity analyses were conducted to examine the effects on the quantitative results from varying the assumptions, structure and techniques of the baseline analysis procedure.     

On designing an unaided authentication service with threat detection and leakage control for defeating opportunistic adversaries

Unaided authentication services provide the flexibility to login without being dependent on any additional device. The power of recording attack resilient unaided authentication services (RARUAS) is undeniable as, in some aspects, they are even capable of offering better security than the biometric based authentication systems. However, high login complexity of these RARUAS makes them far from usable in practice. The adopted information leakage control strategies have often been identified as the primary cause behind such high login complexities. Though recent proposals havemade some significant efforts in designing a usable RARUAS by reducing its login complexity, most of them have failed to achieve the desired usability standard. In this paper, we have introduced a new notion of controlling the information leakage rate. By maintaining a good security standard, the introduced idea helps to reduce the login complexity of our proposed mechanism − named as Textual-Graphical Password-based Mechanism or TGPM, by a significant extent. Along with resisting the recording attack, TGPM also achieves a remarkable property of threat detection. To the best of our knowledge, TGPM is the first RARUAS, which can both prevent and detect the activities of the opportunistic recording attackers who can record the complete login activity of a genuine user for a few login sessions. Our study reveals that TGPM assures much higher session resiliency compared to the existing authentication services, having the same or even higher login complexities. Moreover, TGPM stores the password information in a distributed way and thus restricts the adversaries to learn the complete secret from a single compromised server. A thorough theoretical analysis has been performed to prove the strength of our proposal from both the security and usability perspectives. We have also conducted an experimental study to support the theoretical argument made on the usability standard of TGPM.     

Nonlinear analysis techniques of block masonry walls in nuclear power plants

Concrete masonry walls have been used extensively in nuclear power plants as non-load bearing partitions serving as pipe supports, fire walls, radiation shielding barriers, and similar heavy construction separations. When subjected to earthquake loads, these walls should maintain their structural integrity. However, some of the walls do not meet design requirements based on working stress allowables. Consequently, utilities have used non-linear analysis techniques, such as the arching theory and the energy balance technique, to qualify such walls. This paper presents a critical review of the applicability of non-linear analysis techniques for both unreinforced and reinforced block masonry walls under seismic loading. These techniques are critically assessed in light of the performance of walls from limited available test data. It is concluded that additional test data are needed to justify the use of nonlinear analysis techniques to qualify block walls in nuclear power plants.     

Development of a dairy-based exopolysaccharide bioingredient

An exopolysaccharide (EPS)-producing Streptococcus thermophilus was used to develop an “all-dairy” ingredient with increased EPS content and greater functionality for dairy applications such as Mozzarella cheese. In laboratory-scale trials, milk protein hydrolysate (MPH), whey protein isolate (WPI) and whey protein hydrolysate (WPH) in reconstituted low-heat skim milk powder (LHSMP) were examined as additional dairy protein sources to increase the production of EPS. WPH supplementation resulted in the greatest EPS production. In batch fermentation, a medium based on LHSMP and WPH, combined with optimum conditions of temperature and pH, was used to obtain maximum production of EPS from S. thermophilus. EPS production was growth associated. The fermented biomass was harvested at the end of the exponential phase and freeze-dried. The reduced viable cell count and the retention of ropiness of the powder from the drying process enabled a higher level of EPS inoculation in a preliminary Mozzarella cheese manufacturing trial.     

Formation of dialyzable iron during in-vitro digestion and extraction of mycoprotein

Mycoprotein is the biomass of the fungus Fusarium venenatum. The ability of mycoprotein to enhance production of dialyzable iron following in-vitro digestion or extraction was studied, with the aim of identifying the components responsible. Digested mycoprotein, extracted mycoprotein and digested chicken breast muscle all produced about ten times as much dialyzable iron as the control. All of the dialyzable iron from mycoprotein was ferric. Essentially all the dialyzable iron passed through a 1 kDa molecular weight cut-off membrane. Iron binding components were extracted from mycoprotein using weak acid but not water. Extraction of mycoprotein produced both dialyzable and non-dialyzable components, which bound ferric iron. Analysis of the digests and the dialyzable fraction of acid extraction showed that they contained siderophores, which contributed to the formation of dialyzable iron.     

Influence of shear in the crystallization of polyethylene in the presence of SWCNTs

It is well accepted that due to epitaxy matching, carbon nanotubes are good nucleating agent for linear polyethylene. We demonstrate that not only in the quiescent conditions but also at the relatively low shear rates the presence of single-walled carbon nanotube (SWCNT) accelerates the crystallization kinetics of polyethylene (PE). The influence of SWCNTs on the crystallization kinetics in the quiescent condition is followed with the help of rheological and differential scanning calorimetry studies. The influence of flow on the stretch of the polymer chain is probed using time-resolved small-angle X-ray scattering (SAXS) and is verified with the Deborah number. SAXS data indicates that the strong shearing conditions (shear rate > 50/s for 1 s) are requisite to form shish-kebab structure in the neat polymer. However, for the low shear (shear rate < 50/s for 1 s), the shish-kebab structure that arises due to chain orientation is enhanced in the presence of SWCNTs. The development of oriented structures in SWCNT/PE composites and their absence in the neat polymer under low shear rate indicates that the presence of SWCNTs plays a significant role in the chain orientation. Overall, the results manifest the influence of SWCNTs on chain relaxation of the polymer.     

Incineration of diesel particulate matter using induction heating technique

Incineration of diesel particulate matter for the regeneration of a mesh-type particulate-filter is achieved using induction heating technique. Heating of the diesel particulates deposited on the mesh-type particulate-filter at around 600 °C is investigated. In the case of the particulate filter, stainless-steel mesh-type filters are considered and the influence on filtering efficiency, the engine performance due to back-pressure generation is studied. Theoretical estimation shows that induction heating approach for the regeneration via exhaust gas heating requires high power (>3 kW). On the other hand, regeneration of mesh-type particulate-filter using induction heating technique requires a low input power of around 0.5 kW in the off-line condition. The proposed mesh-type particulate-filter allowed a filtration efficiency of around 30–40% at lower engine speeds and part loads. Particulate combustion through induction heating at static condition is studied and power required for mesh-type filter and sintered metal filter regeneration during engine operation is estimated theoretically.     

Development of Fe‐, Sb‐, Bi‐ and Al‐impregnated silica catalysts using rice husk silica as a support for Friedel–Crafts benzylation of arenes

The milling by‐product of rice, rice husk, constitutes a major waste of the agricultural industry. It is mainly used as a fuel additive for various purposes, leaving behind residual ash which is rich in silica (Biogenic silica). In the present project, rice husk silica was impregnated with Fe³⁺, Sb³⁺, Bi³⁺ and Al³⁺ from both their aqueous and organic solutions. The resultant catalysts were activated at 120 °C and 550 °C and used for the Friedel–Crafts benzylation of benzene using benzyl chloride. Copyright © 2003 Society of Chemical Industry