Intelligent application of fault detection and isolation on HVAC system

University of Technology, Sydney. Faculty of Engineering and Information Technology.Efficient heating, ventilation, and air-conditioning (HVAC) systems are one of the big challenges today around the world. The fault detection and isolation (FDI) play a significant role in the monitoring, repairing and maintaining of technical systems for the final destination of safety and cost reduction. FDI makes an infrastructure to effectively reduce total cost of maintenance and thus increases the capacity utilization rates of equipment. Reduction of energy wasting in the system by real-time fault detection is another goal. Among all HVAC system’s studies, the focus of this thesis is on developing of fast and reliable FDI structure that can cover all subsections of HVAC system including cooling tower, chiller and air handling units (AHU) which greatly affect building energy consumption and indoor environment quality. The first stage of this study is to develop and validates a mathematical HVAC model then follows by simulation and sensitivity analysis. The simulation makes a good capability of producing artificial fault free and faulty data for review of any upcoming failure over the HVAC system. These data with wide range of fault severities can be used to assess the performance of HVAC automated fault detection and isolation (AFDI) system. Two categories of process history diagnosis methods have been reviewed and assessed for the development of AFDI algorithms at second stage of this study. Principal component analysis (PCA) and support vector machine (SVM) classification are two chosen algorithm which have been analysed in depth and initially tested by simulated data from stage one. This review has been continued by developing online SVM algorithm with incremental learning technique and then tested both on simulated and operational data. An experimental rig is designed and applied in the last stage of this research. This setup is configured inside the HVAC laboratory of UTS to collect operational data for the operating test. Operational data as outcome of this stage was then used for test of developed AFDI from last stage. Artificial neural network (ANN) algorithm compressed in frame of black box model for fault free reference. Finally, a combination of black box model and developed AFDI was tested and evaluated for cooling tower and air handling unit (AHU) faults based on operational data. The result shows increasing of robustness, performance and accuracy for the proposed AFDI over the operational data

A study on influencing factors on brand loyalty: A case study of Mobile industry

Brand loyalty plays essential role on product development especially in mobile industry. In this paper, we present an empirical survey to study the effects of different factors including brand associate, brand awareness, distribution intensity and quality perception on brand loyalty. The proposed model of this paper is examined by designing a questionnaire consists of 16 questions in Likert scale and distributing it among 200 people who use a particular brand in mobile industry called Nokia. The results are analyzed using structural equation modeling where Cronbach alpha is calculated as 0.84. The results indicate that there is a positive relationship between perception quality as well as brand awareness and brand loyalty. In addition, there is a positive relationship between brand awareness and perception quality

Synthesis of Silver Nanowires with Reduced Diameters Using Benzoin-Derived Radicals to Make Transparent Conductors with High Transparency and Low Haze.

Reducing the diameter of silver nanowires has been proven to be an effective way to improve their optoelectronic performance by lessening light attenuation. The state-of-the-art silver nanowires are typically around 20 nm in diameter. Herein we report a modified polyol synthesis of silver nanowires with average diameters as thin as 13 nm and aspect ratios up to 3000. The success of this synthesis is based on the employment of benzoin-derived radicals in the polyol approach and does not require high-pressure conditions. The strong reducing power of radicals allows the reduction of silver precursors to occur at relatively low temperatures, wherein the lateral growth of silver nanowires is restrained because of efficient surface passivation. The optoelectronic performance of as-prepared 13 nm silver nanowires presents a sheet resistance of 28 Ω sq-1 at a transmittance of 95% with a haze factor of ∼1.2%, comparable to that of commercial indium tin oxide (ITO)

A report about a rare case of tail gut cyst (TGC) in a 90-year-old man with sacrum ulceration

مقدمه: تیلگات کیست (Tailgut cyst=TGC) یک ضایعه کیستیک غیر شایع با منشا بقایای رودهPostnatal است که در فضای خلف رکتوم ایجاد می گردد. گزارش مورد: آقای 90 ساله اهل میناب با شکایت زخم در ناحیه ساکروم در مرکز آموزشی درمانی شهید صدوقی یزد پذیرش شد. بیمار در گرفتن شرح حال همکاری لازم را نداشت. بعد از انجام آزمایشات معمول، بیمار تحت عمل جراحی قرار گرفت و ناحیه مربوطه از نظر ترشحات تخلیه و ترمیم شد و طی عمل جراحی به توده ای در ناحیه ساکروم برخورد گردید، بعد از برش کامل و خارج کردن آن در بررسی آسیب شناسیTGC تشخیص داده شد. نتیجه گیری: با اینکه بروز بدخیمی در تیلگات کیست نادر است ولی باید در تشخیص افتراقی، تمام تومورهای خلف رکتوم به ویژه در زنان میانسال مورد توجه قرار گیرد

Estimating compressive strength of concrete containing untreated coal waste aggregates using ultrasonic pulse velocity

In recent years, the overuse and exploitation of coal resources as fuel in industry has caused many environmental problems as well as changes in the ecosystem. One way to address this issue is to recycle these materials as an alternative to aggregates in concrete. Recently, non-destructive tests have also been considered by the researchers in this field. As there is limited work on the evaluation of the compressive strength of concrete containing coal waste using non-destructive tests, the current study aims to estimate the compressive strength of concrete containing untreated coal waste aggregates using the ultrasonic pulse velocity (UPV) technique as a non-destructive testing approach. For this purpose, various concrete parameters such as the compressive strength and UPV were investigated at different ages of concrete with different volume replacements of coarse and fine aggregates with coal waste. The test results indicate that 5% volume replacement of natural aggregates with untreated coal waste improves the average compressive strength and UPV of the concrete mixes by 6 and 1.2%, respectively. However, these parameters are significantly reduced by increasing the coal waste replacement level up to 25%. Furthermore, a general exponential relationship was established between the compressive strength and the UPV associated with the entire tested concrete specimens with different volume replacement levels of coal waste at different ages. The proposed relationship demonstrates a good correlation with the experimental results

Bone density may affect primary stability of anterior cruciate ligament reconstruction when organic core bone plug fixation technique used

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Purpose: Core Bone Plug Fixation (CBPF) technique is an implant-less methodology for ACL reconstruction. This study investigates the effect of bone density on CBPF stability to identify the bone quality that is likely to benefit from this technique. Methods: Artificial blocks with 160 (Group 1), 240 (Group 2), and 320 (Group 3) kg/m3 densities were used to simulate human bone with diverse qualities. These groups are representative of the elderly, middle age and young people, respectively. A tunnel was made in each test sample using a cannulated drill bit which enabled harvesting the core bone plug intact. Fresh animal tendon grafts were prepared and passed through the tunnel, so the core bone was pushed in to secure the tendon. The fixation stability was tested by applying a cyclic load following by a pullout load until the failure occurred. The selected group was compared with interference screw fixation technique as a gold standard method in ACL reconstruction. Results: The Group 2 stiffness and yield strength were significantly larger than Group 1. The graft slippage of Group 1 was significantly less than Group 3. The ultimate strengths were 310 N and 363 N, in Groups 2 and 3, significantly larger than that of Group 1. The ultimate strength in fixation by interference screw was 693.18 N, significantly larger than the bone plug method. Conclusions: The stability of CBPF was greatly affected by bone density. This technique is more suitable for young and middle-aged people. With further improvements, the CBPF might be an alternative ACL reconstruction technique for patients with good bone quality. Clinical relevance: The CBPF technique offers an implant-less organic ACL reconstruction technique with numerous advantages and likely would speed up the healing process by using the patient’s own bones and tissues rather than any non-biologic fixations.Peer reviewe

Bioinformatics Evaluation of Plant Chlorophyllase, the Key Enzyme in Chlorophyll Degradation

Background and Objective: Chlorophyllase catalyzes the hydrolysis of chlorophylls to chlorophyllide and phytol. Recently, several applications including removal of chlorophylls from vegetable oils, use in laundry detergents and production of chlorophyllides have been described for chlorophyllase. However, there is little information about the biochemical characteristics of chlorophyllases.Material and Methods: 35 chlorophyllase protein sequences were obtained from the National Centre for Biotechnology Information database. All of the sequences were analyzed using bioinformatics tools for their conserved domain, phylogenetic relationships and biochemical characteristics.Results and Conclusion: The overall domain architecture of chlorophyllases consisted of the esterases/lipases superfamily domain over their full length and the alpha/beta hydrolase family domain over the middle part of their sequences. Plant chlorophyllases could be classified into 4 clades. Molecular weight and pI of the chlorophyllases ranged 32.65-37.77 kDa and 4.80-8.97, respectively. The most stable chlorophyllase is probably obtained from Malus domestica. Chlorophyllases form Solanum pennellii, Triticum aestivum, Triticum urartu, Arabidopsis lyrata, Pachira macrocarpa, Prunus mume and Malus domestica were predicted to be soluble upon overexpression in Escherichia coli, Beta vulgaris and Chenopodium album chlorophyllases were predicted to form no disulfide bond. Chlorophyllases from Jatropha curcas, Amborella trichopod, Setaria italica, Piper betle, Triticum urartu and Arabidopsis thaliana were predicted to be in non-N-glycosylated form.Conflict of interest: The authors declare no conflict of interest

Online support vector machine application for model based fault detection and isolation of HVAC system

Abstract—Preventive maintenance plays an important role in Heating, Ventilation and Air Conditioning (HVAC) system. One cost effective strategy is the development of analytic fault detection and isolation (FDI) module by online monitoring the key variables of HAVC systems. This paper investigates realtime FDI for HAVC system by using online Support Vector Machine (SVM), by which we are able to train a FDI system with manageable complexity under real time working conditions. It is also proposed a new approach which allows us to detect unknown faults and updating the classifier by using these previously unknown faults. Based on the proposed approach, a semi unsupervised fault detection methodology has been developed for HVAC system