Development of extrusion on demand for ceramic freeze-form extrusion fabrication processes

Freeze-form Extrusion Fabrication (FEF) is a Solid Freeform Fabrication method. It involves the deposition of a ceramic paste in a layer by layer manner to construct a three dimensional structure. The ceramic paste used in this process consists of a high solids loading of ceramic powder mixed with water and a nominal amount of an aqueous organic binder. These characteristics make the process environmentally friendly. Also the absence of dies or molds in the process makes it suitable for fabrication of materials like ceramics. In the past, parts have been fabricated with continuous extrusion of a ceramic paste. In FEF, Extrusion on Demand (EOD) refers to the ability to control the start and stop paste extrusion on command. Extrusion on Demand makes possible the fabrication of parts with complex geometries and internal features. The extrusion force is an important aspect to be controlled for the successful implementation of EOD in FEF. A general tracking controller with integral action is implemented to allow precise tracking of the reference force. Two possible methods of achieving EOD by controlling extrusion force and fine tuning process parameters have been discussed. Experiments are conducted to tune the controller and process parameters. Working ranges for all process parameters have been established. Three dimensional ceramic structures have been fabricated by using the parameter values obtained from the experiments --Abstract, page iv

Design Optimization of a Capacitive Sensor for Mass Measurement of Nanometer-Sized Exhaust Carbon Particles

Nanometer-sized carbon particulates generated by incomplete combustion in heavy-duty vehicles are harmful to human health. A high-resolution technique is needed to detect and measure these pollutants. This study aims to optimize a capacitive sensor design for detecting and measuring particulates. Firstly, the effect of design parameters on particulate detection and sensor compliance sensitivity is investigated by using the finite element method. By comparing the simulation results with literature findings for performance validation, the sensor structure is optimized to detect lower particulate concentrations. The simulation result shows that particulate detection sensitivity has linear variations with changes in particulate mass. With optimum electrode spacing and top insulation layer thickness of 5 µm, the sensor can detect a particulate deposition of 0.033 mg/min and generate a maximum capacitance of 581 pF. Since the optimized design can measure particulate deposition at a lower range and with higher sensitivity, it is suitable to be applied to detect nanometer-sized carbon particulates

Quality of Service (QoS) routing algorithm for Software Defined Network (SDN)

Due to the use of various technologies like mobile, cloud, big data. The network traffic has increased this has resulted in the  re examination of the working of  traditional network architectures as these are built as static architectures and cannot handle the rapid growing traffic on the internet. A dynamic architecture which can be programmed according to the traffic behaviour was the need. Software Defined Networking (SDN) was emerged to address the growing needs of the dynamic traffic which has been in the moonlight since 2010. SDN increase and makes the network as flexible to program according to the programmers needs by keeping the traffic in line. It gives the user flexibility of adjusting the network resources by separating the control plane and data plane. By using SDN networks can be managed dynamically. The capacity of a network to offer good services to the selected network traffic over various technologies is termed as Quality of Service (QoS). To transfer high-bandwidth video and multimedia information continuously QoS is of particular objective.Â

An efficient technique for lossless address data compression using adaptive SPIHT Algorithm in WSN

The computer is becoming more and more powerful day by day. Data compression is a popular approach to reducing data volumes and hence lowering disk I/O and network data transfer times. While several lossy data compression techniques have demonstrated excellent compression ratios, lossless data compression techniques are still among the most popular ones. Sensor networks represent a non-traditional source of information, as readings generated by sensors flow continuously, leading to an infinite stream of data. Sensors are non-reactive elements which are used to monitor real life phenomena, such as live weather conditions, network traffic, etc. They are usually organized into networks where their readings are transmitted using low level protocols

Performance Comparison of Layered Composite Bimodal Fiber Mats with Unimodal Fiber Mats

The study was conducted to evaluate and compare performance of unimodal and bimodal mats with approximately same mass. 10% and 18% Nylon 4, 6 polymer solution were used for electrospinning the fibers. A negative ion source was used to neutralize the surface charge. The fiber diameters were measured with SEM and were \u3c500 nm thus incorporating the slip effect. Bimodal mats were prepared from different deposition modes. Optimal mode was selected on analyzing the performance factors. The bimodal mats were then compared with unimodal mats. For their performance the fiber mass for these mats was approximately the same. It was observed that the unimodal mats had higher efficiencies and higher pressure drop giving a lower FOM. Bimodal mats showed lower efficiencies and pressure drop compared to unimodal mats. However, the FOM for bimodal mats was approximately 200% higher than unimodal mat

Modeling the formation, evolution, and observation of first stars

Population III (Pop III) stars are the first generation stars forming after the big bang from primordial gas. This dissertation is focused on the various processes that suppress and delay the formation of Pop III stars in the universe and their implications for the observations. We studied the impacts of the Lyman-Werner (LW) radiation that dissociates molecular hydrogen, baryon-dark matter streaming velocity introduced at recombination, ionizing radiation from nearby galaxies, and a model for the composition of dark matter known as the fuzzy dark matter on the formation of Pop III stars. Firstly, we take a closer look at the critical halo mass (Mcrit) that is the typical minimum dark matter halo mass needed to host cold dense gas to form the first stars using cosmological hydrodynamical simulations. LW radiation that dissociates molecular hydrogen and the baryon-dark matter streaming velocity both delay the formation of Pop III stars by increasing the critical halo mass. We describe our simulation suite with varying levels of LW radiation and streaming velocity to provide a fit for Mcrit as a function of LW radiation, streaming velocity, and redshift which can be used in semi-analytic models of early galaxy formation to make predictions for observations. Secondly, we explore a possible mechanism for the formation of large clusters of Pop III stars: a nearby ionizing source that ionizes a late forming halo, delaying its collapse until the halo is sufficiently large enough that the core can self-shield and suffer runaway collapse. We use numerical simulations to examine the fragmentation of the gas near the runaway collapse using the simple estimates and sink particles to show that the number of fragments is generally small, at most a handful, and that the mass accretion rate on the fragments is of order 10⁻³ Msun/yr. This rate is sufficiently high enough that the descent on the main sequence (and hence the suppression of accretion) is delayed until the stellar masses are of order 100-1000 Msun, but not high enough to produce direct collapse black holes of mass ~ 10⁵ Msun. The resulting clusters are larger than those produced in minihalos but are still likely to fall short of being easily detectable in James Webb Space Telescope blind fields. Finally, we investigate the formation of the first stars and galaxies in a fuzzy dark matter cosmology. Fuzzy dark matter, made up of ultra-light axions of mass ~ 10⁻²² eV, is a proposed alternative to the standard cold dark matter to solve its apparent small-scale problems. Its large de Broglie wavelength, of the order of kpc, results in the suppression of small-scale matter power, thus delaying the formation of the first stars and galaxies to lower redshift in much more massive halos. Therefore, first stars can be used to put very strong constraints on the mass of the fuzzy dark matter. We describe our cosmological simulations that accurately evolve the fuzzy dark matter distribution to study the formation of the first stars and galaxies

Sharing economy-based on-demand peer-to-peer tutoring and resource sharing

The sharing economy is a socio-economic ecosystem built around the sharing of human and physical resources. This is considered to be a new and alternate socio-economic system which is currently in its early stages and has tremendous potential. The sharing economy combines the need to direct demand towards supply by adding the point of view of collaboration based on the social networks and preferences of various entities involved. This is based on the economic model of Collaborative Consumption in which participants share access to resources rather than having individual ownership over them. We propose the novel idea of a sharing economy-based model for knowledge sharing amongst peers in a classroom setting. Students often find themselves stuck on trivial implementation details like syntax, best practices and which tools to use. Many times, help is difficult to find, even though the solution might be known to one of the student's peers. Moreover, many large classes do not have enough teaching assistants to help out students and the use of such a platform can be useful to offload simple questions within the classroom itself, saving office hours for more complex questions. This, coupled with the benefits of a collaborative learning environment for students, has motivated us towards the development of an on-demand peer-to-peer tutoring and knowledge sharing platform. Such a platform can also help us understand how different incentive mechanisms motivate people to share knowledge: Are people motivated by social reputation or money? We develop an Android application called "Quet" which can be used by students to request help from their peers for questions related to their coursework on-demand. Preliminary observations show that an application like Quet is useful; and we wish to deploy this in multiple courses in subsequent semesters to realize its full potential and utility to students and instructors alike

Effect of yoga practices on Hs-CRP in Indian railway engine drivers of metropolis

Objectives: To examine the effect of yoga training on high sensitivity C reactive protein (hs-CRP) and lipid profile levels in railway engine drivers working in metropolis. Methods: Male drivers of Indian railways, age ranged from 30 to 42 yrs with no known medical disorders, were randomized to yoga group (n=16) and control group (n=16). At the baseline and after completion of one month yoga training both the groups were assessed for hs-CRP and lipid profile levels. The yoga group practiced in a set of yoga techniques for 1 hr. daily in the morning along with daily routine work, while control group engaged in daily routine work only. Results: Statistically significant reduction (

Health needs, access to healthcare, and perceptions of ageing in an urbanizing community in India: a qualitative study.

BACKGROUND: India's elderly population is rising at an unprecedented rate, with a majority living in rural areas. Health challenges associated with ageing, changing social networks and limited public health infrastructure are issues faced by the elderly and caregivers. We examined perceptions of health needs of the elderly across local stakeholders in an urbanizing rural area. METHODS: The qualitative study was conducted among participants in the Andhra Pradesh Children and Parents Study (APCAPS) site in Rangareddy district, Telangana. We collected data using focus group discussions and interviews among communities (n = 6), health providers (n = 9) and administrators (n = 6). We assessed stakeholders' views on the influence of urbanization on health issues faced and interventions for alleviating these challenges. We used a conceptual-analytical model to derive themes and used an inductive approach to organizing emerging codes as per a priori themes. These were organized as per thematic groups and ranked by different authors in order of importance. Bronfebrenner's theory was used to understand stakeholder perspectives and suggest interventions within four identified spheres of influence - individual, household, community and services. RESULTS: Stakeholders reported frailty, lack of transport and dependence on others as factors impacting health access of the elderly. Existing public health systems were perceived as overburdened and insensitive towards the elderly. Urbanization was viewed positively, but road accidents, crime and loneliness were significant concerns. Interventions suggested by stakeholders included health service outreach, lifestyle counseling, community monitoring of healthcare and engagement activities. CONCLUSIONS: We recommend integrating outreach services and lifestyle counseling within programs for care of the elderly. Community institutions can play an important role in the delivery and monitoring of health and social services for the elderly