The present article presents critical aspects of RF system development process and its sequential phases along with associated challenges. It also discusses importance of active and passive components thermal behavior and their impact in overall system performance. The study on performance deviation of these components with temperature change has been reported. Potential issues for gain variation and frequency selectivity have been analysed and suitable solutions are explored accordingly. Implementation of temperature stabilization method in designed RF product has been carried out during prototype development. Practical achieved results are noted down during testing and measurement to monitor effectiveness of thermal stabilization mentioned in it. Finally, wideband flat gain response has been achieved by implementation of thermal stabilization for active and passive components to avoid any performance degradation.

A component attachment process and noise sustain mechanism have been proposed in this article to realize a quad channel high gain phase-matched receiver. A critical issue in the conventional soldering process is the formation of unwanted voids beneath the component which affects gain and phase performances of the system under consideration at microwave frequencies. Assembly conditions and process sequence followed by bonding process for oscillation-free flat gain, low noise figure (NF), and sustain phase noise performance are selected to ensure less than 2% void formation. Vapor phase assembly (VPA) at 250 degrees is performed in case of longer RF track PCBs for avoidance of any phase mismatch. Experimentations on assembly conditions, number of bonding stands, and bond wire thickness are carried out for multiple trails respectively. In each step, X-ray scan reports and monitored performance results have been analyzed to set checkpoints in the complete development process. Finally, gain, NF, and phase noise responses of developed multichannel receivers have been analyzed. Multichannel pulse repetition time (PRT) controlled microwave module has been realized and tested over thermal screening for several cycles and performed random vibration (RV) test to validate the proposed component attachment process. Electrical parameter results achieved using proposed techniques have been compared with conventional method results in this article. The proposed component attachment process is equally applicable to the realization of any other RF circuit design to be operated under ambient conditions and harsh environments.

This article analyzes and describes phase nonlinearity reduction techniques in detail for ultra wideband complex receivers to qualify airborne system requirements. Phase nonlinearity directly affects the final frequency resolution coming from unknown threats. Thereby, the reduction of phase nonlinearity of all radio frequency (RF) channels including phase correlators is very essential. A simple phase nonlinearity calculation step has been shown in this article without taking the help of any coding (software). A detail excel sheet-based phase nonlinearity calculation has been explained and estimated with examples. Power and phase corrections are especially done to keep the RF response flat over a wide frequency spectrum to enhance better phase linearity. This is done by designing various equalizers with different slope gradients and adjusting power levels by using attenuation pads or reducing feeds by other means. Phase nonlinearity has been kept under control by tracking the phase of mixers, other passive/active components within +/- 5 degrees, and all the RF channels within +/- 15 degrees. The power level has been adjusted within P1dB or just beyond the P1dB to keep the harmonic level less, which in turn controls phase nonlinearity in all the active devices. The performance of phase correlators against various power levels has been analyzed to finalize uniform RF and LO power levels (feed) at the input of the phase correlators. The level of uniform feed has been decided after reviewing phase nonlinearity responses of the correlators. Thus, the final resolved frequency become accurate (<3 MHz root mean square). Finally, four receivers have successfully been developed and evaluated over temperature (-40 degrees C to +71 degrees C) and vibration to establish the method for mass production.

This paper present unique design technique of 4 channel downconverter receiver for monopulse AESA based target tracking radar. Sum and difference channels are designed along with Guard channel which possess extra gain requirement and stringent noise figure as per system requirements. Supportive calibration mechanism via innovative switch circuitry is incorporated along with Guard channel thus avoids need of dedicated additional channel. In line with system needs design methodology is chosen, block diagram is developed, circuit and EM simulations are carried out in ADS, CST and Cascade software and critical aspects of designing such receiver are also disclosed.

“Right the First Time” principle is to reduce the number of gear hobbing process rejection rate, reason of rework, scrap and change orders so customers are dissatisfied. The main objective of this project is to produce the first time right robust product, without setting piece rejection, also increasing the consistent product quality and productivity. While the machine setting changes, the first piece gets scrap due to improper tool selection and improper process parameters in Pfauter PE1000 machine for hobbing and skiving operation. In every setting change in Pfauter PE1000 machine for part number of 1000904, the first piece gets scrapped. To reduce the setting piece rejection rate, we found a proper root causes that are (1) part nominal height, (2) fixture locating height and (3) hob diameter. The permanent corrective action to prevent that setting rejection in Pfauter for part number of 1000904 is to measure the part with TRIMOS, dial gauge, coordinate measuring machine and micrometer that reduces the rejection rate from 14 to 1. Initial inspection, hob diameter and hob nomenclature are also reassigned to prevent the setting piece rejection. By advanced product quality planning, the Six Sigma value is increased from 3.9 to 4.9 and the rejection rate is decreased from 7458 to 441 PPM.

The purpose of this paper is to disclose improved crystal based frequency source system covering design techniques and experimental methodologies for the stabilization of phase noise performance of X-band phase-locked loop (PLL) at 10.6 GHz. Phase noise performance of PLL-based unit under test (UUT) is prone to disturbance occurred in random vibration profile frequency spectrum. UUT self-resonance plays vital role in occurrence of disturbance in random vibration profile. The stabilization of phase noise performance during dynamic (random) vibration condition is achieved by following methodologies, i.e. vibration-isolator compensation techniques, purification tactic for reference crystal of PLL, and spatial location analysis for finding out mounting position of reference crystal. Spatial analysis helps to filter out UUT self-resonance frequency from random vibration spectrum which leads to reduction of frequency resonance pickups during random vibration testing.

In today’s global economy, the survival of companies depends on their ability to innovate and improve quickly. Metal Inert Gas (MIG) welding can apply for many kinds of material such as mild steel, carbon steel, stainless steel, aluminum. This paper deals with the fabrication of MIG welding fixtures to clamp work piece and reduce the rejection ratio in production and reduce the welding distortion. The automation is used to welding the work piece for increasing the quality and production. Fixtures are essential components of the manufacturing process because they are required in most automated manufacturing, inspection, and assembly operations. The device is provided to support and control the work area with fixture providing a linear motion by the motor. Using fixing and automation welding often eliminates the need for verification, positioning, personal marking, and the same quality in the manufacturing process. These increase productivity and reduce operating time compared to manual welding. Automation welding process gives a best result compared to the manual welding. Some of the issues are occurred during manual welding (welding distortion, imperfect welding, less quality, and lower production rate). These problems can be solved by using automation welding process. In welding distortion, the automation rate of welding capacity increases 50% compared to manual welding rate. In imperfect welding joint, the fixture setup helps us to weld the work piece with 45% more efficiently.

Some critical investigations on direct substrate-attachment process over double-sided metallic housing have been discussed in this article under wideband instantaneous frequency measurement receiver development in detail. Conventional reflow method-based substrate-attachment techniques have many issues when the surface area becomes larger. One of the major issues is that it forms unwanted voids beneath the substrate, which affects phase performances at higher frequencies. To overcome these issues, a direct substrate-attachment process has been carried out under inert environment using a customized vaporphase assembly (VPA) process. The final temperature and its profile have been readjusted by tuning gradient and duration of rise, equilibrium, and fall times to customize the VPA process. Conventional methods are compared with VPA of direct substrate attachment for large (phi approximate to 265 mm) surface area. Experimentations of direct substrate attachments are carried out for diverse quality of nickel (Ni)- and silver (Ag)-plated housings, respectively. In each step of plating depth, the percentage of impurities in plating and X-ray scan reports have been analyzed to make crucial decisions about attachment improvement, and limits have been set for mass production. Modules have been made and tested over extensive thermal cycling from -40 degrees C to +71 degrees C and random vibrations in three axes to establish the analysis.

Aim of this work is to remove an oil effluent from water. While disaster of ships or boats in ocean, lake or pond makes hazardous for environment of aquatic fauna and flora. Oil spills is a major problems in many countries and industries to facing a situation to remove an oil from water. In oil skimmer coated using Teflon or activated carbon for separator systems of roller. Roller absorbs the oil from water and gliding and collecting through scrapper. The collected oil can reused in many purpose and some oil will be toxic or reusable.

The PEMAMEK is a panel processing machine after 6 years of usage the overall equipment effectiveness (O.E.E) of machine is gradually reduced to 50%. To improve O.E.E of machine, initial analysis is taken on availability, performance and quality. The company is expecting to produce 250 m sub-panel for every 120 min, but actual is 110 m. To improve the O.E.E, used the Work Study and Time study method. Actual availability of machine is 45%, which is increased to 70% by properly using manpower and reducing rework of welding, availability time of the PEMAMEK has been improved efficiently. (C) 2019 Elsevier Ltd. All rights reserved.

The purpose of this paper is to give temperature compensation techniques for active components and better design methods for passive circuits for robust trans-receiver modules used in airborne radar application. Performance of any trans-receiver module is dependent on active or passive components used in it. Gain stabilization techniques for mitigating any performance deviation are discussed. Parameter variation like gain, selectivity with temperature changes are shown later, compensation technique and method are discussed for elimination of such issues with active or passive blocks of any trans-receiver system. Finally, practical implementation of suggested compensation techniques and methods for performance stabilization are shown which are necessary for making high robust trans-receivers for electronic system used in airborne application.

This article presents design and implementation of discrete components based ultra-wideband high speed SPDT switch. Here switch and equalizer are designed separately and integrated with LNA in a single housing. Individual semi active and passive components are designed in 2½ D and 3D full wave EM simulator for 1–18 GHz frequency. Layout implementation of whole circuit has been in CPWG technique instead of normal microstrip line for achieving more isolations between nearest two arms at highest frequencies. Then full system analysis is carried out in 2½ D software of all components. Very high speed driver also designed using simple transistor and NAND gate circuits. Measured results of the proposed switch are found in good agreement with the simulated results.

This paper describes the assembly process improvement of die attachment technique of an open-loop multistep voltage-controlled attenuator (VCA) in detail. The VCA is made up of p-i-n diodes (dies). Die p-i-n diodes suffer from attachment issues done by single or binary epoxy followed by controlled temperature treatment. It results in improper ground impedance at microwave and millimeter-wave applications. A thorough analysis is carried out on these epoxy attachment issues. A suitable technique for the attachment of dies on the metallic standoff is adopted to overcome these issues for the mass production scenario. Multiple modules have been made and tested over extensive thermal cycling from -30 degrees C to +70 degrees C, and random vibrations in three axes to establish the analysis.

This paper proposes a design of broadband microwave gain equalizer with asymmetric parabolic gain-slope profile to compensate the gain variations of the amplifier over frequency. Since the gain blocks (i.e. amplifiers or tubes) typically follows asymmetric parabolic nature over the frequency, an equalization circuit with desired attenuation control is necessary to compensate while maintaining the parabolic nature of equalization. The simulated results show that the proposed design of gain slope equalization has an asymmetric performance from 1.5 GHz to 10 GHz with good impedance matching and profile selectivity. Equalization curve is very much suitable to meet the practical requirements of amplifiers flat gain response of wide band receivers for modern electronic warfare.

Recurrent pregnancy loss (RPL) affects 2-3% of couples. Despite a detailed work-up, the etiology is frequently undefined, leading to non-targeted therapy. Viable embryos and placentae express PreImplantation Factor (PIF). Maternal circulating PIF regulates systemic immunity and reduces circulating natural killer cells cytotoxicity in RPL patients. PIF promotes singly cultured embryos' development while anti-PIF antibody abrogates it. RPL serum induced embryo toxicity is negated by PIF. We report that PIF rescues delayed embryo development caused by <3 kDa RPL serum fraction likely by reducing reactive oxygen species (ROS). We reveal that protein disulfide isomerase/thioredoxin (PDI/TRX) is a prime PIF target in the embryo, rendering it an important ROS scavenger. The 16F16-PDI/TRX inhibitor drastically reduced blastocyst development while exogenous PIF increased >2 fold the number of embryos reaching the blastocyst stage. Mechanistically, PDI-inhibitor preferentially binds covalently to oxidized PDI over its reduced form where PIF avidly binds. PIF by targeting PDI/TRX at a distinct site limits the inhibitor's pro-oxidative effects. The >3kDa RPL serum increased embryo demise by three-fold, an effect negated by PIF. However, embryo toxicity was not associated with the presence of putative antiPIF antibodies. Collectively, PIF protects cultured embryos both against ROS, and higher molecular weight toxins. Using PIF for optimizing in vitro fertilization embryos development and reducing RPL is warranted.

Grinding is a process for final completion of components to ensuring smooth surfaces and high tolerances. When comparing with other operations, grinding is, the costlier process that is used under optical conditions. AISI 317L material was surface finished under various input parameters. Since it is more hardness and non- magnetic material. The main objective of the work is to study the grinding behavior and obtaining the optimal operating process parameters. It consists of several parameters such as chemical composition of work piece, depth of cut, wheel speed, feed rate, grain size, etc. The main objective of grinding process is to minimize the surface roughness value, which is to be identified in this paper.

A study on the physiochemical properties of semi-refined carrageenan (SRC) derived from low industrial grade seaweed (LIGS) were conducted and compared to semi-refined carrageenan from high-grade seaweed (HGS) of Kappaphycus Alvarezii and others researches. The morphology of SRC (LIGS and HGS) was investigated through scanning electron microscopy (SEM) and physiochemical properties of SRC through Fourier Transform Infrared (FTIR) analysis, particle size analyser, proximate composition (moisture, ash, acid insoluble ash, acid insoluble matter), sulphate and mineral content by inductively coupled plasma optical emission spectrometry (ICP-OES), colour, pH, viscosity and gel strength. SRC-HGS showed smaller particle size than SRC-LIGS from SEM and particle size analysis. SRC-LIGS exhibited lowest lightest, but highest yellowness, with L* and b* values reported 57.77 and 15.9, respectively. The gel strength of SRC-LIGS was lower than SRC-HGS. The SRC-LIGS show a comparable thermal properties, sulphur and mineral content, ash, acid insoluble ash and moisture content from SRC-HGS, which suggest that these SRC-LIGS have good potential as renewable resources materials.

Semi-refined carrageenan (SRC) product is considerably cheaper and easier to produce as a natural polysaccharide, which was utilized in food and other product application. However, the application in latex is limited. The aim of this work is to evaluate the SRC produced from low industrial grade seaweed (LIGS) in the latex foam application. The FTIR spectra showed the SRC produced as kappa type carrageenan with lower sulfur content compared to native LIGS. NR latex foam is produced by using the Dunlop method with some modifications. The effect of SRC loading as a secondary gelling agent in NR latex foam is investigated. The density and morphology of the NR latex foam with the addition of the SRC are analyzed. NR latex foam density increased with SRC loading and peaked at 1.8 phr SRC. The addition of SRC has induced the bigger cell size compared to the cell size of the control NR latex foam, as shown in the optical micrograph. It can be concluded that SRC LIGS could be acted as secondary gelling agent in NR latex foam.

This article explains finding of power issues and the methodology of giving a suitable solution for performance stabilization of an ultra-wideband very high gain receiver with steep gain gradient. The origin of this problem lies in homodyning down conversion technique itself. Its LO is derived from input RF source. Varieties of frequency band limited equalizers like RC, RL and RLC are examined to overcome initial gain fluctuations at low frequencies as well as region based gain humps to reduce slope gradient. Thereby at the same time it helps to enhance practically achievable gain against theoretical gain at around highest frequencies by reducing power distribution among all harmonic and spurious components caused by lower frequency elements.

This research discussed the influenced of different preparation methods of Carrageenan fillers as new natural biodegradable additives in Natural Rubber (NR) latex compound. NR latex compounds with addition of 2 phr Carrageenan fillers was prepared through normal pre-vulcanization method which the NR latex compound was subjected to 70oC denoted as Method 1. The preparation of NR latex compounds with 2 phr Carrageenan fillers without temperature is denoted as Method 2. The unfilled NR Latex films also was prepared as a control through Method 1. The crosslink density and mechanical properties of NR Latex films were investigated via swelling test and mechanical testing (tensile and tear) respectively. The swelling test results shows that Method 2 have highest crosslink density where the crosslink density and mechanical properties via Method 1 shows a decreased value. This may contribute from the hydration of carrageenan at temperature of 40oC-70oC. The experimental results indicate that the addition of carrageenan with elimination of pre-vulcanization step is mainly responsible for the enhancement of crosslink density and mechanical properties compared to Method 1. Method 2 gives higher crosslink density, tear strength and lower modulus as evaluated from the mechanical properties. Carrageenan can be added as natural filler in NR Latex films with gives better interaction between rubber matrix and fillers with softer NR latex films which required in NR latex products especially gloves.