Preconditioned conjugate-gradient methods for low-speed flow calculations

An investigation is conducted into the viability of using a generalized Conjugate Gradient-like method as an iterative solver to obtain steady-state solutions of very low-speed fluid flow problems. Low-speed flow at Mach 0.1 over a backward-facing step is chosen as a representative test problem. The unsteady form of the two dimensional, compressible Navier-Stokes equations is integrated in time using discrete time-steps. The Navier-Stokes equations are cast in an implicit, upwind finite-volume, flux split formulation. The new iterative solver is used to solve a linear system of equations at each step of the time-integration. Preconditioning techniques are used with the new solver to enhance the stability and convergence rate of the solver and are found to be critical to the overall success of the solver. A study of various preconditioners reveals that a preconditioner based on the Lower-Upper Successive Symmetric Over-Relaxation iterative scheme is more efficient than a preconditioner based on Incomplete L-U factorizations of the iteration matrix. The performance of the new preconditioned solver is compared with a conventional Line Gauss-Seidel Relaxation (LGSR) solver. Overall speed-up factors of 28 (in terms of global time-steps required to converge to a steady-state solution) and 20 (in terms of total CPU time on one processor of a CRAY-YMP) are found in favor of the new preconditioned solver, when compared with the LGSR solver

The dynamic of the discursive construction of Europeanness and Eastness in the European Union’s discourse on Ukraine, 2004-2016

https://www.ester.ee/record=b5298519*es

Self Meta Pseudo Labels: Meta Pseudo Labels Without The Teacher

We present Self Meta Pseudo Labels, a novel semi-supervised learning method similar to Meta Pseudo Labels but without the teacher model. We introduce a novel way to use a single model for both generating pseudo labels and classification, allowing us to store only one model in memory instead of two. Our method attains similar performance to the Meta Pseudo Labels method while drastically reducing memory usage.Comment: Accepted by IEEE ICMLA 202

Multiple-part-type production scheduling for high volume manufacturing (token-based approach)

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaf 46).Multiple-part-type production scheduling is a common industrial problem with no generalized solution. In this thesis, a systematic approach is presented to aid in the mentioned production decision making in an actual factory. This strategy involves first generating production targets by optimization followed by a real-time scheduling (token-based) method --- the Control Point Policy. Based on the simulation results, the proposed strategy is able to schedule the production effectively. In addition, it was demonstrated that there was a tradeoff between the amount of inventory and the number of changeovers. Keywords: Multiple-part-type, production scheduling, optimization, token-based Disclaimer: The content of the thesis is modified to protect the real identity of the attachment company. Company name and confidential information are omitted.by Sing Hng Ng.M.Eng

Kajian Kesan Abu Sekam Padi Ke Atas Sifat-Sifat Pematangan Dan Fizikal Bagi Getah Asli Terepdksida

Daism projek ini, potensi abu sekam padi putih (ASPP) sebagai sat4 pengisi baru bagi ENR·-25 telah dikaji. I<aj ian yang dijalankan adalah berdasarkan sifat-sifat pematangan seperti masa pematangan (T90 ) dan tork maksimum dan juga sifat-sifat fizikal seperti kekuatan tensil, kel~ua tan eabi kan, - modul us, pemanj angan lpada takat putus serta kekerasan. I n this resea rch proj ect, the potential of whi te rice husk ash (WRHA) as a new filler in ENR-25 has been studied. The effects of WRHA in cure properties such as cure time (T90) and maximum torques as well as physical properties such as tensile trength, tear strength, modulus, elongation at break and hardess have been investigated

Offline Chemical Wash for Internal Fouled Multistage Pump

Case StudiesHigh pressure lean amine pump performance dropped within a span of about 1 month due to internal fouling. Fouling was caused by accumulation of iron sulphide. To address the fouling, pump would have been to taken out of service for a full overhaul, resulting in extended downtime and high cost of repair. Offline chemical wash with 1% EDTA (Ethylenediaminetetraacetic) solution pursued as an alternative to the pump overhaul. Prior to commencing with the chemical wash, material compatibility of pumps/mechanical seals wetted parts, and process fluid flow path were considered as part of the technical evaluation. The chemical wash skid comprised of an external circulation tank and air operated diaphragm pump. Skid was connected to the pump via flexible hoses. During chemical wash, samples were regularly collected at the circulation outlet to check for appearance in order to determine progress of the chemical wash in removing the foulants. Pump performance recovered upon completion of the chemical wash

Factors influencing purchase intention of organic food among Malaysians in post Covid-19 pandemic: health consciousness as the mediator

The World Health Organization (WHO) designated the coronavirus epidemic of 2019, also known as COVID-19, which was initially found in Wuhan, China in November 2019. The global outbreak of coronavirus on March 11, 2020, has caused a shift toward a "new normal" in both societal norms and commercial operations. Nevertheless, there is still a lack of comprehension regarding Malaysian consumers’ preferences and decisions in purchasing goods and services. In this study, a total of 212 valid questionnaires were obtained in order to examine consumer purchase intention toward organic food in the post-pandemic period. The data collection was conducted across entire Malaysia using an online questionnaire approach. The study results showed that health consciousness, subjective norms, and food safety trust influence the organic food purchase intention of Malaysian consumers. Meanwhile, the findings also reveal that health consciousness mediates the relationship between environmental concern, subjective norms, and food safety knowledge with organic food purchase intention during the post-pandemic period. As a result, the study is extremely helpful for organic food industry players in comprehending the purchase behavior of Malaysian consumers in times of post-Covid-19. Therefore, it is believed that greater efforts to spread information about health benefits and food safety among consumers would be supported in encouraging consumer buy intentions of organic food. In addition, the findings of this result will create more chances for a similar research topic to be carried out in the future

Replication of Alphaviruses: A Review on the Entry Process of Alphaviruses into Cells

Alphaviruses are small, enveloped viruses, ~70 nm in diameter, containing a single-stranded, positive-sense, RNA genome. Viruses belonging to this genus are predominantly arthropod-borne viruses, known to cause disease in humans. Their potential threat to human health was most recently exemplified by the 2005 Chikungunya virus outbreak in La Reunion, highlighting the necessity to understand events in the life-cycle of these medically important human pathogens. The replication and propagation of viruses is dependent on entry into permissive cells. Viral entry is initiated by attachment of virions to cells, leading to internalization, and uncoating to release genetic material for replication and propagation. Studies on alphaviruses have revealed entry via a receptor-mediated, endocytic pathway. In this paper, the different stages of alphavirus entry are examined, with examples from Semliki Forest virus, Sindbis virus, Chikungunya virus, and Venezuelan equine encephalitis virus described

Steam Turbine High Axial Displacement due to Governor Actuator Filter Clog

Case StudiesThe governor actuator for a steam turbine was observed to be hunting and failed to maintain stable operating speed. The steam turbine is used to drive a centrifugal compressor for H2 service in a recycle loop. The extent of speed oscillating was exaggerating over time and caused excessive turbine axial movement. The unit was forced to shut down to prevent secondary damage due to turbine high axial movement. The steam turbine was overhauled approximately 9 months prior to the incident. Oil flushing was performed, lube oil was changed out and main oil filters were replaced as part of machinery overhaul scope. The main oil filter elements were inspected during troubleshooting of this event and were badly fouled with blackish substance. The governor actuators were inspected and the internal filters for the oil supply line were clogged with soft, blackish substance. Foulant analysis was performed using Energy Dispersive X-ray (EDX) which identified the main component to be Carbon. De- gassing tank oil was drained out and observed layer of blackish substance. EDX identified the main component to be identical to that found in main oil filter. Water sample from de-gassing tank bottom drain was tested and the pH was 3-4 (i.e. acidic). Further troubleshooting revealed that fine carbon particles were carried over from upstream and mixing with the process gas prior to the unit shut down for the compressor train overhaul. The presence of carbon particles had contaminated the seal oil and control oil circuit which then clogged up the actuator internal fine filters (~40um). This case study presents the unusual phenomenon, troubleshooting tools, recovery process and key learnings which provide user operating with similar service a reference

Telecom InP/InGaAs nanolaser array directly grown on (001) silicon-on-insulator

A compact, efficient, and monolithically grown III–V laser source provides an attractive alternative to bonding off-chip lasers for Si photonics research. Although recent demonstrations of microlasers on (001) Si wafers using thick metamorphic buffers are encouraging, scaling down the laser footprint to nanoscale and operating the nanolasers at telecom wavelengths remain significant challenges. Here, we report a monolithically integrated in-plane InP/InGaAs nanolaser array on (001) silicon-on-insulator (SOI) platforms with emission wavelengths covering the entire C band (1.55 μm). Multiple InGaAs quantum wells are embedded in high-quality InP nanoridges by selective-area growth on patterned (001) SOI. Combined with air-cladded InP/Si optical cavities, room-temperature operation at multiple telecom bands is obtained by defining different cavity lengths with lithography. The demonstration of telecom-wavelength monolithic nanolasers on (001) SOI platforms presents an important step towards fully integrated Si photonics circuits