Feasibility Study of Virtual Target Scoring Using High‐Speed Imaging Techniques

Measurements of consistency and accuracy are standard techniques to assess the performance of a weapon in case of direct fire kill mechanism. It is often determined from the scoring pattern of a witnessing target erected at a known distance in an open range making use of an in‐line CCD camera with suitable long‐range optics or using an array of acoustic/optical sensors in the close vicinity of the target. In the case of indoor range, acoustic and optical sensors are used to determine the same preferably for small‐caliber ammunitions. However, all these indirect methods are subjected to the constraint of triangulation error. In case of high‐caliber ammunitions, especially fired from tank guns, witnessing targets and acoustics methods are used although it is time‐consuming and labor‐intensive in nature. To overcome these difficulties a virtual scoring method is proposed. Herein, a high‐speed video camera is used for in‐line image acquisition of the projectile at the desired distance using long‐range optics. The virtual target is defined making use of an optical detector placed at the target distance and under the trajectory, where a trigger is generated when the projectile passes over it. This hardware trigger is sent to the high‐speed video camera and then the spatial coordinates of the projectile in the virtual plane is determined off‐line making use of necessary image processing and image analysis. A feasibility study of this technique was performed in a scaled‐down model and laid down in greater details.     

Microclimatic modeling of the urban thermal environment of Singapore to mitigate urban heat island

This study investigates the urban heat island effect in Singapore and examines the key factors causing this effect. The possibilities of improving heat extraction rate by optimizing air flow in selected hot spots were explored. The effect of building geometry, façade materials and the location of air-conditioning condensers on the outdoor air temperature was explored using computational fluid dynamics (CFD) simulations. It was found that at very low wind speeds, the effect of façade materials and their colours was very significant and the temperature at the middle of a narrow canyon increased up to 2.5 °C with the façade material having lower albedo. It was also found that strategically placing a few high-rise towers will enhance the air flow inside the canyon thereby reducing the air temperature. Adopting an optimum H/W ratio for the canyons increased the velocity by up to 35% and reduced the corresponding temperature by up to 0.7 °C.     

Composition and Recyclability Analysis of Poly(Vinyl Chloride) Recovered from Computer Power Cables and Commercial Wires

The product‐based recycling of the electrical and electronic devices and their by‐products are limited due to their complex characteristics and dissimilar material characteristics. However, such recycling procedures give clear ideas about the composition and possible recycling options of the materials present in them. Consequently, the present study deals with isolation and recycling of the major polymeric fraction present in the waste computer power supply cables (CPS) and electrical power supply (EPS) wires isolated from the household items. The composition analysis of CPS and EPS indicates that the poly(vinyl chloride) (PVC) is the major polymeric fraction along with minor content of polyethylene (PE) and polycarbonate (PC). Further, this research compares the mechanical recyclability of the PVC recovered from the CPS and EPS. Among the PVC's analyzed, PVC isolated from the EPS has been indicated superior mechanical properties. Similarly, thermal degradation analysis (TGA) indicated higher thermal stability for the PVC isolated from EPS. Besides, the flammability of the PVC specimens was studied and concluded with the possible mechanism occurring during combustion. Moreover, this study points out that PVC recovered from EPS and CPS can be mechanically recycled for the elimination of the waste. J. VINYL ADDIT. TECHNOL., 26:213–223, 2020. © 2019 Society of Plastics Engineers     

Effect of MQL and nanofluid on the machinability aspects of hardened alloy steel

Abstract

The current research comprises of various machinability aspects of 4340 hardened alloy steel which are scrutinized with in context of improvements in main cutting force, tool flank wear, crater wear, surface roughness, micro-hardness, machined surface morphology, chip morphology, chip reduction coefficient and apparent coefficient of friction under three different cutting fluid applications i.e. compressed air, water soluble coolant and nanofluid (using eco-friendly radiator coolant as the base fluid and Al₂O₃ as the nanoparticle) using uncoated cermet cutting inserts and a comparative assessment was performed to select which fluid performed better in terms of various machining attributes among three cutting fluids. The minimum quantity lubrication technique (MQL) was used in which a smaller volume of coolant sprinkled at high pressure. This method is found as the most effective alternative to minimize health risks and machining costs, which is quite high in other setups. The test specimen was machined at three different cutting speeds i.e. 100, 120 and 140?m/min along with two machining parameters i.e. feed and depth of cut were kept constant respectively at 0.2?mm/rev and 0.4?mm. Outcomes made a conclusion that Al₂O₃ enriched ecofriendly nanocoolant outperformed both compressed air and water soluble coolant in terms of every machinability aspects.     

Influence of organically modified nanoclay on the performance of pineapple leaf fiber‐reinforced polypropylene nanocomposites

Polypropylene/Pine apple leaf fiber (PP/PALF)‐reinforced nanocomposites were fabricated using melt blending technique in a twin‐screw extruder (Haake Rheocord 9000). Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of nanoclay in PP/PALF composites were investigated. It was observed that the tensile, flexural, and impact properties of PP increase with the increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % PALF and 5 wt % MA‐g‐PP exhibited optimum mechanical performance with an increase in tensile strength to 31%, flexural strength to 45% when compared with virgin PP. Addition of nanoclay results in a further increase in tensile and flexural strength of PP/PALF composites to 20 and 24.3%, which shows intercalated morphology. However, addition of nanoclay does not show any substantial increase in impact strength when compared with PP/PALF composites. Dynamic mechanical analysis tests revealed an increase in storage modulus (E′) and damping factor (tan δ), confirming a strong influence between the fiber/nanoclay and MA‐g‐PP. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties when compared with the virgin matrix. TEM micrographs also showed few layers of agglomerated clay galleries along with mixed nanomorphology in the nanocomposites. Wide angle X‐ray diffraction studies indicated an increase in d‐spacing from 22.4 Å in Cloisite 20A to 40.1 Å in PP/PALF nanocomposite because of improved intercalated morphology. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Microscale analysis of patterning reactions via FTIR imaging: Application to intelligent hydrogel systems

A novel application of FTIR imaging for real-time characterization of patterning polymerization processes with microscale spatial resolution is presented. These methods will enable the microscale analysis of the reactions of polymeric systems with various substrates and devices. Specifically, intelligent hydrogels containing ionic groups (pH responsive) and poly(ethylene glycol) have been micropatterned onto gold surfaces, and the free-radical polymerization reaction has been characterized. It was demonstrated that differences in the reaction rates across a patterned region could be successfully resolved and characterized. This novel characterization method based on FTIR imaging will facilitate the optimization of integration processes of patterned polymeric films leading to enhanced (and reproducible) application of these materials as functional components in a variety of microdevices.     

Conditional Loss of the Exocyst Component Exoc5 in Retinal Pigment Epithelium (RPE) Results in RPE Dysfunction,Photoreceptor Cell Degeneration,and Decreased Visual Function

To characterize the mechanisms by which the highly conserved exocyst trafficking complex regulates eye physiology in zebrafish and mice, we focused on Exoc5 (also known as sec10), a central exocyst component. We analyzed both exoc5 zebrafish mutants and retinal pigmented epithelium (RPE)-specific Exoc5 knockout mice. Exoc5 is present in both the non-pigmented epithelium of the ciliary body and in the RPE. In this study, we set out to establish an animal model to study the mechanisms underlying the ocular phenotype and to establish if loss of visual function is induced by postnatal RPE Exoc5-deficiency. Exoc5^−/− zebrafish had smaller eyes, with decreased number of melanocytes in the RPE and shorter photoreceptor outer segments. At 3.5 days post-fertilization, loss of rod and cone opsins were observed in zebrafish exoc5 mutants. Mice with postnatal RPE-specific loss of Exoc5 showed retinal thinning associated with compromised visual function and loss of visual photoreceptor pigments. Abnormal levels of RPE65 together with a reduced c-wave amplitude indicate a dysfunctional RPE. The retinal phenotype in Exoc5^−/− mice was present at 20 weeks, but was more pronounced at 27 weeks, indicating progressive disease phenotype. We previously showed that the exocyst is necessary for photoreceptor ciliogenesis and retinal development. Here, we report that exoc5 mutant zebrafish and mice with RPE-specific genetic ablation of Exoc5 develop abnormal RPE pigmentation, resulting in retinal cell dystrophy and loss of visual pigments associated with compromised vision. Together, these data suggest that exocyst-mediated signaling in the RPE is required for RPE structure and function, indirectly leading to photoreceptor degeneration.     

Revolute manipulator workspace optimization: A comparative study

Robotic manipulators with three revolute families of positional configurations are very common in the industrial robots. The capability of a robot largely depends on the workspace of the manipulator apart from other parameters. In this work, an evolutionary optimization algorithm based on foraging behavior of Escherichia coli bacteria present in human intestine is utilized to optimize the workspace volume of a 3R manipulator. The proposed optimization method is subjected to some modifications for faster convergence than the original algorithm. Further, the method is also very useful in optimization problems in a highly constrained environment such as the robot workspace optimization. The test results are compared with standard results available using other optimization algorithms such as Differential Evolution, Genetic Algorithm and Particle Swarm Optimization. In addition, this work extends the application of the proposed algorithm to two different industrial robots. An important implication of this paper is that the present algorithm is found to be superior to other methods in terms of computational efficiency.     

Externally pressurized conical step bearing with visco-elastic lubricant

A solution for an externally pressurized conical step bearing with visco-elastic lubricant is obtained by using a regular perturbation technique. The effects of the parameters S (elastic number), H = h₁/h₂ (the ratio of film thickness) and sinα (α, the semi-vertical angle) on the pressure, the load capacity and the ratio of flow flux have been studied and are presented graphically. The effect of elasticity on improving bearing performance is very small.     

Designs of multi-bit sigma delta modulator

This paper presents new design variants of third order multi-bit sigma delta modulator (SDM): low distortion SDM and cascaded SDM. The proposed modulator based on the conventional SDMsuch L-0MASH(Multi-stAge noise SHaping) and interstage feedback topology. TheMASHSDM is not a single loop system. One of the drawback is that performance is limited by uncancelled noise from the first modulator and interstage feedback topology only cancels nonlinear errors introducing by multi-bitDACin the final stage, but the rest stage still containsDACnonlinearity errors without any noise shaping which still degrade overall system performance. An improved version of cascaded multi-bit SDM is proposed to overcome these problems mentioned above. In addition a third order low distortion SDM is also proposed. Simulation results verify the superiority of the both proposed modulator.