Rectangular waveguide narrow-wall longitudinal-aperture antenna arrays for high-power applications

This work deals with the design and bench test of rectangular waveguide narrow-wall longitudinal-aperture antenna arrays for high power applications. The best narrow-wall longitudinal-aperture array designs in the work are called the double-narrow-wall-slot-HPB-array and the double-split-waveguide-HPB-array. The double-narrow-wall-slot-HPB-array (double-split-waveguide-HPB-array) consists of two identical narrow-wall-slot-HPB-arrays (split-waveguide-HPB-arrays) with a common broad wall. All elements of the split-waveguide-HPB-array are identical and are called H-plane-bend-radiators (HPB-radiators). An HPB-radiator is an H-plane bend terminating in a radiating aperture with the narrow dimension of the waveguide flaring out. Optimizing the HPB-radiators performance involves designing its aperture dimensions and the function that determines the H-plane taper to minimize the reflected power into the feed-waveguide while maintaining a half sine wave aperture electric field (E-field) distribution. Once the optimal HPB-radiator is designed, the design of the split-waveguide-HPB-array is similar to designing a uniform linear array. There is minimal mutual coupling between the elements through the waveguide, and for design purposes, external coupling between the elements can be ignored. The first four elements of the narrow-wall-slot-HPB-array are longitudinal-slots in the narrow wall of a rectangular waveguide, and the last element is an HPB-radiator with the same optimal performance criteria as that of the split-waveguide-HPB-array. The narrow-wall-slot-HPB-array is designed by a combination of computational and microwave network analysis techniques. First, computational analysis of the individual slots is performed separately. In the next step, each longitudinal-slot in the narrow wall of the guide is reduced to a lossy two port microwave network whose S-parameters have been obtained from the computational analysis; the loss in the network represents the power radiated by the slot. Finally, microwave network analysis is used to design a uniform linear array with a low reflected power into the feed-waveguide. The primary advantage of the split-waveguide-HPB-array over the narrow-wall-slot-HPB-array is its ability to beam steer since the inputs to its elements can be controlled separately. Since the structures are used for high power applications, the HPB-radiator\u27s H-plane taper function needs to be smooth without any sharp corners. Its design procedure, using just computational or analytical methods, was intractable. The design procedure is therefore formalized using a novel approach, which processes the computational analysis data using iterative search algorithms. This approach is made possible by mapping a design output variable that is computationally intensive, to another that requires much less computational time. This approach is based on a hypothesis that is called the \u27dimensional offset hypothesis\u27. The behavior of narrow-wall longitudinal-slots with dimensions comparable to a free-space wavelength is also characterized. The similarities they possess with wire radiators are presented. The experimental results validate the theoretical analysis results for the design of an HPB-radiator and from the microwave network analysis. The power handling capability analysis for the double-narrow-wall-slot-HPB-array and the double-split-waveguide-HPB-array is also presented.\u2

Circuit designs for low-power and SEU-hardened systems

The desire to have smaller and faster portable devices is one of the primary motivations for technology scaling. Though advancements in device physics are moving at a very good pace, they might not be aggressive enough for now-a-day technology scaling trends. As a result, the MOS devices used for present day integrated circuits are pushed to the limit in terms of performance, power consumption and robustness, which are the most critical criteria for almost all applications. Secondly, technology advancements have led to design of complex chips with increasing chip densities and higher operating speeds. The design of such high performance complex chips (microprocessors, digital signal processors, etc) has massively increased the power dissipation and, as a result, the operating temperatures of these integrated circuits. In addition, due to the aggressive technology scaling the heat withstanding capabilities of the circuits is reducing, thereby increasing the cost of packaging and heat sink units. This led to the increase in prominence for smarter and more robust low-power circuit and system designs. Apart from power consumption, another criterion affected by technology scaling is robustness of the design, particularly for critical applications (security, medical, finance, etc). Thus, the need for error free or error immune designs. Until recently, radiation effects were a major concern in space applications only. With technology scaling reaching nanometer level, terrestrial radiation has become a growing concern. As a result Single Event Upsets (SEUs) have become a major challenge to robust designs. Single event upset is a temporary change in the state of a device due to a particle strike (usually from the radiation belts or from cosmic rays) which may manifest as an error at the output. This thesis proposes a novel method for adaptive digital designs to efficiently work with the lowest possible power consumption. This new technique improves options in performance, robustness and power. The thesis also proposes a new dual data rate flipflop, which reduces the necessary clock speed by half, drastically reducing the power consumption. This new dual data rate flip-flop design culminates in a proposed unique radiation hardened dual data rate flip-flop, Firebird\u27. Firebird offers a valuable addition to the future circuit designs, especially with the increasing importance of the Single Event Upsets (SEUs) and power dissipation with technology scaling.\u2

Metagenomics — A Technological Drift in Bioremediation

Nature has its ways of resolving imbalances in its environment and microorganisms are one of the best tools of nature to eliminate toxic pollutants. The process of eliminating pollutants using microbes is termed Bioremediation. Metagenomics is a strategic approach for analysing microbial communities at a genomic level. It is one of the best technological upgradation to bioremediation. Identification and screening of metagenomes from the polluted environments are crucial in a metagenomic study. This chapter emphasizes recent multiple case studies explaining the approaches of metagenomics in bioremediation in different contaminated environments such as soil, water etc. The second section explains different sequences and function-based metagenomic strategies and tools starting from providing a detailed view of metagenomic screening, FACS, and multiple advanced metagenomic sequencing strategies dealing with the prevalent metagenomes in bioremediation and giving a list of different widespread metagenomic organisms and their respective projects. Eventually, we have provided a detailed view of different major bioinformatic tools and datasets most prevalently used in metagenomic data analysis and processing during metagenomic bioremediation

Progress The Excellence Of Scattered Power Productions

This calculate the current dynamics and harmonics of the parameters to generate the control values to meet the requirements of repeated power while releasing the complete synchronization and used as a new value for ' the driving force of the electric current. This demonstrates the analysis and improvement of the electrical quality (soft wax, swelling and coupling) of the related smart inverter performance used by the distributed generation. The designed controller controls the actual power and motion provided by the DOs in the PCC. The controller is designed to provide current access to the PCC Solidarity agent. The increased demand for power transmission and harmonics in a PCC due to load and resistance changes may have an impact on system costs in a PCC

Analysis of Trickle-bed Reactor for Ethanol Production from Syngas Using Clostridium Ragsdalei

The conversion of syngas components (CO, CO2 and H2) to liquid fuels such as ethanol involves complex biochemical reactions catalyzed by a group of acetogens such as Clostridium ljungdahlii, Clostridium carboxidivorans and Clostridium ragsdalei. The low ethanol productivity in this process is associated with the low solubility of gaseous substrates CO and H2 in the fermentation medium. In the present study, a 1-L trickle-bed reactor (TBR) was analyzed to understand its capabilities to improve the mass transfer of syngas in fermentation medium. Further, semi-continuous and continuous syngas fermentations were performed using C. ragsdalei to evaluate the ability of the TBR for ethanol production. In the mass transfer studies, using 6-mm glass beads, it was found that the overall mass transfer coefficient (kLa/VL) increased with the increase in gas flow rate from 5.5 to 130.5 sccm. Further, an increase in the liquid flow rate in the TBR decreased the kLa/VL due to the increase in liquid hold up volume (VL) in the packing. The highest kLa/VL values of 421 h-1 and 178 h-1 were achieved at a gas flow rate of 130.5 sccm for 6-mm and 3-mm glass beads, respectively. Semi-continuous fermentations were performed with repetitive medium replacement in counter-current and co-current modes. In semi-continuous fermentations with syngas consisting of 38% CO, 5% N2, 28.5% CO2 and 28.5% H2 (by volume), the increase in H2 conversion (from 18 to 55%) and uptake (from 0.7 to 2.2 mmol/h) were observed. This increase was attributed to more cell attachment in the packing that reduced CO inhibition to hydrogenase along the column length and increased the H2 uptake. The maximum ethanol produced during counter-current and co-current modes were 3.0 g/L and 5.7 g/L, respectively. In continuous syngas fermentation, the TBR was operated at dilution rates between 0.006 h-1and 0.012 h-1 and gas flow rates between 1.5 sccm and 18.9 sccm. The highest ethanol concentration of 13 g/L was achieved at dilution and gas flow rates of 0.012 h-1 and 18.9 sccm, respectively. The molar ratio of ethanol to acetic acid of 4:1 was obtained during continuous fermentation which was 7.7 times higher than in semi-continuous fermentations. The improvement of the reactor performance in continuous mode gives scope to explore the TBR as a potential bioreactor design for large scale biofuels production.Biosystems & Agricultural Engineerin

Prosthodontic management of subtotal maxillectomy with minimally invasive interim obturator: a case report

The interim obturator serves as a pathway between the immediate or surgical obturator and the final prosthesis, offering functional and aesthetic benefits until the delivery of the definitive prosthesis. Furthermore, it acts as a guide during the fabrication of the definitive prosthesis, influencing aspects such as prosthesis extension, teeth arrangement, and the positioning of retentive aids. These aids may encompass orthodontic wiring, surgical suturing, and other non-invasive techniques. This case report details a conservative and less invasive method for retaining an interim obturator in maxillectomy patients, providing an alternative approach in prosthodontic care

Designing a Bioreactor for Regenerating High Aspect Ratio Tissues

Many tissues have a high aspect ratio (large surface area relative to the thickness of the matrix) and contain multiple cell types. Effect of flow-through configuration within these systems has not been studied. In these scale-up systems, non-ideal fluid distribution conditions could arise from two possible factors: channeling, and dead zones.This study utilized a circular parallel plate reactor that allows large tissue scaffolds. The objective of this study was to understand the flow distribution in a reactor for growing large tissues (10 cm diameter and 2 mm thick) in vitro and to evaluate the nutrient distribution with consumption for three different cell types (namely hepatocytes, smooth muscle cells and chondrocytes). Simulations were performed using CFD packages CFX 11 for flow distribution without porous structure and Comsol Multiphysics 3.4 for flow distribution with nutrient consumption in the porous structure. The flow distribution simulations were validated by doing residence time distribution experiments. 1. The inlet and outlet locations affect the fluid distribution. 2. Presence of porous structure increased the non ideal flow patterns in the system. 3. Location of inlet and outlet over the porous region resulted in high shear stresses. 4. High shear stress regions were eliminated and better nutrient distribution was observed when the inlet and outlet were moved away from the porous region 5. Nutrients flow rate requirements for the cells to grow varied for different cell typesSchool of Chemical Engineerin

Live Feedback on a Live Video Using HTML5 Canvas

The objective of this research is to teleoperate a robot situated at a remote location with the help of video camera. The operator relies on the live video to move the bot and maneuver different tasks, but in the case of laggy video the operator has to wait until the video is received which is frustrating and tiresome. We intend to solve this by giving feedback to the operator instantly as the command is given. This is done by using HTML5 Canvas as a medium to show the video instead of using a video player. HTML5 Canvas gives us flexibility as it can be used to access pixel values from the video and manipulate them giving feedback to the operator on the video itself. Preliminary data shows 30% decrease in time for doing certain tasks using this system instead of without using the system.Computer Scienc

Framework Quick Rfid Tag Reading in Dense Environments

Radio Frequency Identification (RFID) systems provide a mechanism to automatically identify the objects and collect information about them. The main objective of RFID Medium Access Control (MAC) protocols is to provide an opportunity to RFID readers in identifying multiple tags successfully and efficiently. Several variants of ALOHA and Binary Tree Search protocols are being proposed in this area but they show acceptable performances only if limited number of tags are present in the RFID reader region as fairly low amount of data is going to be exchanged. Their performances degrade when large numbers of tags are present in the region because if multiple tags try to communicate with the reader at the same time, it leads to collisions. This problem becomes more complex in the case of mobile tags because of their limited time presence in the reader's region. In this research, we develop a framework which can be used in conjunction with most of the Framed Slotted ALOHA protocols. A new protocol, Accelerated Framed Slotted ALOHA (AFSA), which is a result of application of the framework with Enhanced Dynamic Frame Slotted ALOHA, not only tries to minimize the number of collisions but also minimizes the total wastage of bandwidth due to collisions and unoccupied slots. We show, through analysis and simulations, our approach gives better average tag reading time over existing models. We further extend our approach to mobile RFID systems where the tags move with a constant velocity in the reader's vicinity.Computer Science Departmen