Compressive Sensing Using Iterative Hard Thresholding with Low Precision Data Representation: Theory and Applications

Modern scientific instruments produce vast amounts of data, which can overwhelm the processing ability of computer systems. Lossy compression of data is an intriguing solution, but comes with its own drawbacks, such as potential signal loss, and the need for careful optimization of the compression ratio. In this work, we focus on a setting where this problem is especially acute: compressive sensing frameworks for interferometry and medical imaging. We ask the following question: can the precision of the data representation be lowered for all inputs, with recovery guarantees and practical performance? Our first contribution is a theoretical analysis of the normalized Iterative Hard Thresholding (IHT) algorithm when all input data, meaning both the measurement matrix and the observation vector are quantized aggressively. We present a variant of low precision normalized {IHT} that, under mild conditions, can still provide recovery guarantees. The second contribution is the application of our quantization framework to radio astronomy and magnetic resonance imaging. We show that lowering the precision of the data can significantly accelerate image recovery. We evaluate our approach on telescope data and samples of brain images using CPU and FPGA implementations achieving up to a 9x speed-up with negligible loss of recovery quality.Comment: 19 pages, 5 figures, 1 table, in IEEE Transactions on Signal Processin

Prediction of yields and composition of char from fast pyrolysis of commercial lignocellulosic materials, organosolv fractionated and torrefied olive stones

peer-reviewedThis study investigated the fast pyrolysis behaviour of torrefied olive stones, fractionated olive stones and lignocellulosic commercial compounds. Olive stones were reacted in a continuous industrial torrefaction unit. The olive stones were also fractionated into their main components in an organosolv reactor at temperatures from 170 to 190 ◦C in both the presence and absence of an acidic catalyst. All samples were reacted in a wire mesh reactor at different temperatures (800–1150 ◦C) and heating rates (400–1150 ◦C/s), and the solid product was characterised for its yield, morphology, and elemental composition. The char yields from fast pyrolysis of commercially available cellulose, hemicelluloses, and lignin were compared with yields of fractionated olive stones. A model was developed to compare the measured yields of olive stones with the predicted yields using fractionated or commercial components. The presence of acid during fractionation had a stronger effect than the temperature, particularly on the lignin fraction. The fractionated lignocellulosic compounds provided more accurate predictions of the char yields of olive stones, as compared to the commercial lignocellulosic compounds. The fractionation at 180 ◦C without acid catalyst gave the cellulose, hemicellulose, and lignin with highest degree of purity and resulted in the most accurate predictions of the experimental yields of olive stones. The results showed that interactions between the lignocellulosic components were not significant. The char yield of each fractioned compound and non-treated olive stones could be accurately predicted from the lignocellulosic content which has importance for biorefinery applications in which each fraction is used as a value-added product

Recent Advances in Health Biotechnology During Pandemic

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which emerged in 2019, cut the epoch that will make profound fluctuates in the history of the world in social, economic, and scientific fields. Urgent needs in public health have brought with them innovative approaches, including diagnosis, prevention, and treatment. To exceed the coronavirus disease 2019 (COVID-19) pandemic, various scientific authorities in the world have procreated advances in real time polymerase chain reaction (RT-PCR) based diagnostic tests, rapid diagnostic kits, the development of vaccines for immunization, and the purposing pharmaceuticals for treatment. Diagnosis, treatment, and immunization approaches put for- ward by scientific communities are cross-fed from the accrued knowledge of multidisciplinary sciences in health biotechnology. So much so that the pandemic, urgently prioritized in the world, is not only viral infections but also has been the pulsion in the development of novel approaches in many fields such as diagnosis, treatment, translational medicine, virology, mi- crobiology, immunology, functional nano- and bio-materials, bioinformatics, molecular biol- ogy, genetics, tissue engineering, biomedical devices, and artificial intelligence technologies. In this review, the effects of the COVID-19 pandemic on the development of various scientific areas of health biotechnology are discussed

TEL ÖRGÜ REAKTÖRÜ KULLANARAK BİYOKÜTLE YAKITLARIN TEK PARÇACIK YANMA ANALİZİ

This thesis investigates the single particle combustion behavior of a Turkish lignite and two agricultural biomass fuels using a recently developed wire mesh reactor coupled with a high-speed camera. The fuels under investigation are endogenous of Turkey and present potential to gradually replace the currently burned lignite coals for electricity generation. This change requires a large amount of data so that the oftentimes disparate fuels can be properly co-fired. The scientific outcome of the study will be understanding the influence of fuel type, particle size and mass, and thermal pre-treatment on parameters such as the ignition delay time and burnout time which are of extreme importance for co-firing purposes. The wire mesh reactor to be used enables conditions that resemble those found in large scale combustion systems (i.e., high temperatures and high heating rates). The fuel particles with different masses were heated to 1000 ºC by radiation with a heating rate of 900ºC/s. To understand the effects of thermal pre-treatment, fuels are torrefied, slow and fast pyrolyzed. The time analysis demonstrated that the particle mass and size did not affect ignition delay time; however, slow pyrolysis had a significant effect on the ignition delay time. The ignition delay time was tremendously increased for the chars produced from slow pyrolysis (~10 s) compared to raw (~3 s) and other heat-treated vi particles (~4 s) for all fuels. Burnout times of all fuels increased proportionally with particle mass. Fast and slow pyrolysis generally increased the char combustion and burnout times. The average burnout times for chars from fast and slow pyrolysis of biomass was ~20 s and ~29 s, respectively, while those of raw biomass was ~9 s. The average burnout times for chars from fast and slow pyrolysis of lignite was ~20 s and ~53 s, respectively, while those of raw lignite was ~19 s, when 2 mg particles were compared. Chars from fast pyrolysis of both biomasses had similar burnout times (~20 s) compared to the that of raw Tunçbilek Lignite (~19 s). This depicts the potential of co-firing TL with biomass chars produced from fast pyrolysis.Bu tez, yüksek hızlı bir kamera ile birleştirilmiş yeni geliştirilen bir tel örgü reaktörü kullanarak birkaç biyokütle yakıtının tek parçacık yanma davranışını araştırıyor. İncelenmekte olan yakıtlar Türkiye’ye özgüdür ve halihazırda yakılan linyit kömürlerini elektrik üretimi için aşamalı olarak değiştirme potansiyeli sunmaktadır. Bu değişiklik, büyük ölçüde veri gerektirir; böylece, zaman zaman bağımsız yakıtlar, uygun şekilde birlikte ateşlenebilir. Çalışmanın bilimsel sonucu, yakıt türü, partikül büyüklüğü ve termal ön işlemin, ateşleme gecikme süresi ve yanma süresi gibi birlikte ateşleme amaçları için çok önemli olan parametreler üzerindeki etkisi olacaktır. Kullanılacak tel örgü reaktörü, büyük ölçekli yanma sistemlerinde bulunanlara (örneğin, yüksek sıcaklıklar ve yüksek ısıtma hızları) benzeyen koşulları sağlar. Farklı kütlelere sahip yakıt partikülleri, 900ºC/s ısıtma hızıyla radyasyonla 1000 ºC'ye ısıtıldı. Termal ön işlemin etkilerini anlamak için yakıtlar kavruldu, yavaş ve hızlı bir şekilde piroliz edildi. Zaman analizi, partikül kütlesinin ve boyutunun tutuşma gecikme süresini etkilemediğini göstermiştir; fakat, yavaş piroliz, tutuşma gecikme süresi üzerinde önemli bir etkiye sahipti. Yavaş pirolizden (~10 s) üretilen çarlar için tutuşma gecikme süresi, ham (~3 s) ve diğer ısıl işlem görmüş partiküllere (~4 s) kıyasla, tüm yakıtlar icin muazzam derecede artmıştır. Tüm yakıtların yanma viii süreleri partikül kütlesi ile orantılı olarak artmıştır. Hızlı ve yavaş piroliz genellikle çar yanmasını ve yanma sürelerini artırmıştır. Biyokütlenin hızlı ve yavaş pirolizinden oluşan çarların ortalama tükenme süreleri sırasıyla ~20 s ve ~29 s iken, ham biyokütleninki ~9 s idi. 2 mg partiküller karşılaştırıldığında, linyitin hızlı ve yavaş pirolizinden oluşan çarların ortalama yanma süreleri sırasıyla ~20 s ve ~53 s iken, ham linyitinki ~19 s idi. Her iki biyokütlenin hızlı pirolizinden elde edilen çarlar, ham linyit (~19 s) ile karşılaştırıldığında benzer tükenme sürelerine (~20 s) sahipti. Bu, linyitin hızlı pirolizden üretilen biyokütle çarları ile birlikte yakma potansiyelini göstermektedir.M.S. - Master of Scienc

Fast pyrolysis of Turkish hazelnut shell by using novel wire mesh reactor

The present paper studies fast pyrolysis of Turkish hazelnut shell under various conditions in a novel wire mesh reactor (WMR). Particular emphasis was given to understand volatile yield at high heating rates at elevated temperatures. Volatile yields from fast pyrolysis (~3000 ºC/s) showed higher values from both as received (80 wt.%) and dried fuels (85 wt.%) than proximate analysis (PA) (75 wt. %) done at low heating rates (20 ºC/min). Brunauer–Emmitt–Teller (BET) surface analysis was carried out to determine surface areas from the chars obtained from WMR tests

The effect of torrefaction, slow, and fast pyrolysis on the single particle combustion of agricultural biomass and lignite coal at high heating rates

© 2021 Elsevier LtdThe present paper studies single particle combustion of olive residue (OR), almond shell (AS), and Tunçbilek lignite (TL) and their thermal pre-treated particles in a vertical wire mesh reactor (WMR) setup. Pre-treatment of the fuels was done via torrefaction, slow, and fast pyrolysis. The particles with different masses were heated to 1000 °C by radiation with a heating rate of 900 °C/s. The combustion process was recorded with a high-speed camera. The time analysis demonstrated that the particle mass and size did not affect ignition delay time; however, slow pyrolysis had a significant effect on the ignition delay time. The ignition delay time was significantly increased for the chars produced from slow pyrolysis compared to raw and other heat-treated particles for all fuels. Burnout times of all fuels increased proportionally with particle mass. Fast and slow pyrolysis generally increased the char combustion and burnout times. The average burnout times for fast and slow pyrolyzed biochars were ∼20 s and ∼29 s, respectively, while those of raw biomass were ∼9 s. The average burnout times for fast and slow pyrolyzed lignite particles was ∼20 s and ∼53 s, respectively, while those of raw lignite was ∼19 s, when 2 mg particles were compared. Fast pyrolyzed biomass particles had similar burnout times compared to those of raw TL particles. This depicts the potential of co-firing TL with biomass chars produced from fast pyrolysis

Uncertainty calculations and calibration of metal hardness testing equipment

Hardness tests have vital role for industries such as aerospace, ground vehicles and energy. In these industries, companies do not have only their internal processes but also sub-contractors. Therefore, for acceptance tests, hardness testing becomes so convenient way in order to confirm conformance of incoming materials to the facility. Additionally, there are also critical test limits that comes from technology transfer projects. In these type of projects, specification limits can be very narrow and design of parts may not be changed and quality (non-conformance) decisions may not be taken as rework or used as. In case of probable failure, material parts could cause catastrophic results in mentioned industries. In this study, hardness test capability of a Vickers Hardness Machine is investigated by use of direct and indirect calibration methods. Uncertainty calculations are made for Vickers test system. While making calibration of hardness test machines, the parts which are components of hardness scales shall be also calibrated / verified. These components must be in necessary tolerances related to EN/ISO specifications. After that, calibration of these hardness test machines are made by use of hardness reference blocks that are produced and calibrated by national metrology institute or an accredited laboratory