Search results for: high cut-off frequency

Authors: Mohamed El Morsy, Gabriela Achtenová

Abstract:

Condition monitoring is used to increase machinery availability and machinery performance, whilst reducing consequential damage, increasing machine life, reducing spare parts inventories, and reducing breakdown maintenance. An efficient condition monitoring system provides early warning of faults by predicting them at an early stage. When a localized fault occurs in gears, the vibration signals always exhibit non-stationary behavior. The periodic impulsive feature of the vibration signal appears in the time domain and the corresponding gear mesh frequency (GMF) emerges in the frequency domain. However, one limitation of frequency-domain analysis is its inability to handle non-stationary waveform signals, which are very common when machinery faults occur. Particularly at the early stage of gear failure, the GMF contains very little energy and is often overwhelmed by noise and higher-level macro-structural vibrations. An effective signal processing method would be necessary to remove such corrupting noise and interference. In this paper, a new hybrid method based on optimal Morlet wavelet filter and autocorrelation enhancement is presented. First, to eliminate the frequency associated with interferential vibrations, the vibration signal is filtered with a band-pass filter determined by a Morlet wavelet whose parameters are selected or optimized based on maximum Kurtosis. Then, to further reduce the residual in-band noise and highlight the periodic impulsive feature, an autocorrelation enhancement algorithm is applied to the filtered signal. The test stand is equipped with three dynamometers; the input dynamometer serves as the internal combustion engine, the output dynamometers induce a load on the output joint shaft flanges. The pitting defect is manufactured on the tooth side of a gear of the fifth speed on the secondary shaft. The gearbox used for experimental measurements is of the type most commonly used in modern small to mid-sized passenger cars with transversely mounted powertrain and front wheel drive: a five-speed gearbox with final drive gear and front wheel differential. The results obtained from practical experiments prove that the proposed method is very effective for gear fault diagnosis.

Keywords: wavelet analysis, pitted gear, autocorrelation, gear fault diagnosis

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Authors: Biswarup Mukherjee, Aniruddha Ghoshal

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In this paper, we propose a new technique for implementing a low power high speed full adder using 8 transistors. Full adder circuits are used comprehensively in Application Specific Integrated Circuits (ASICs). Thus it is desirable to have high speed operation for the sub components. The explored method of implementation achieves a high speed low power design for the full adder. Simulated results indicate the superior performance of the proposed technique over conventional 28 transistor CMOS full adder. Detailed comparison of simulated results for the conventional and present method of implementation is presented.

Keywords: high speed low power full adder, 2-T MUX, 3-T XOR, 8-T FA, pass transistor logic, CMOS (complementary metal oxide semiconductor)

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Authors: Rozeena Shaikh, Syed M Shahid, Jamil Ahmad, Qaisar Mansoor, Muhammad Ismail, Abid Azhar

Abstract:

Introduction: Diabetes mellitus (DM) is a prevalent non-communicable disease worldwide. In most high-income countries as well as middle-income and low- income countries. DM is among the top causes of deaths. DM may lead to many vascular complications like hypertension, nephropathy, retinopathy, neuropathy, and foot. Diabetic nephropathy (DN) characterized by persistent albuminuria is a leading cause of end stage renal failure (ESRF). Pathogenesis of diabetic nephropathy is implicated by the polymorphisms in genes encoding the components of reninangiotensin- aldosteron system (RAAS) which include angiotensinogen (AGT), angiotensin-II receptor and particularly angiotensin converting enzyme (ACE) gene. Method: Study subjects include 110 control, 110 patients with DM without hypertension, 110 patients with DM with hypertension and 110 patients with DN. Blood samples were collected for Biochemical analysis and PCR and sequencing for the specific region of both genes. Results: The frequency of DD genotype and D allele of ACE (I/D) was significantly (p<0.05) high in DM normotensive, DM hypertensive and DN patients when compared to control. The ACE G2350A genotypes and allele frequencies were significantly different (p<0.05) in DM hypertensive patients as compared to control and DN, while no difference was observed between DM normotensive and DN when compared to control. The genotypes and alleles of AGT (M268T) polymorphism were significantly different (p<0.05) in DM normotensive, DM hypertensive and DN when compared to control. Conclusion: The DD genotype and D allele of ACE (I/D), GG genotype and G allele of ACE (G2350A) and the TT genotype and T allele of AGT (M268T) polymorphism have shown a significant difference in genotype and allele frequencies between controls and patients.

Keywords: genetic variations, ACE, AGT, diabetes mellitus, diabetic nephropathy, Pakistan

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Authors: Mourad Bakouka, Abdelaziz Rabehi

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Companies need to have logistics and transportation in place that can adapt to the changing nature of construction sites. This ensures they can react quickly when needed. A study was conducted to develop a way to locate and track materials on construction sites. The system is an RFID/GPS integration that's required to pull off this feat. The study also reports how the platform has been used in construction. They found many advantages to using it, including reductions in both time and costs as well as improved management of materials orders. . For example, the time in which a project could start up was shortened from two weeks to three days with just a single digital order. As of now, the technology is still limited in its widespread adoption due largely to overall lack of awareness and difficulty connecting to it. However, as more and more companies embrace it in construction, the technology is expected to become ubiquitous. The developed platform provides contractors and construction managers with real-time information about the status of materials and work, allowing them to better manage the workflow in a project. The study sheds new light on this subject, which is essential to know. This work is becoming increasingly aware of the use of smart tools in constructing buildings.

Keywords: materials management, internet of things (IoT), radio frequency identification (RFID), construction site, supply chain management

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Authors: Avijit Datta

Abstract:

We have presented a phase control scheme in population transfer using chirped laser fields. A chirped pulse can do population transfer from one level to another level via adiabatic rapid passage accessible by one photon dipole transition. We propose to use a pair of phase-locked chirped pulses of the same frequency w(t) instead of a singly chirped-pulse frequency w(t). Simultaneous action of phase controlled interference in addition to rapid adiabatic passages due to chirped pulses lead to phase control over this population transfer dynamics. We have demonstrated the proposed phase control scheme over the population distribution from the initial level X(v=0,j=0) to C(v=2,j=1) level of hydrogen molecule using a pair of phase-locked and similarly chirped laser pulses. We have extended this two-level system to three-level 1+1 ladder system of hydrogen molecule from X level to final J(v=2,j=2) level via C intermediate level using two pairs of laser pulses having frequencies w(t) and w'(t) respectively and obtained laudable control over the population distribution among three levels. We also have presented some results of interference effects of w₁(t) and its third harmonics w₃(t).

Keywords: phase control, population transfer, chirped laser pulses, rapid adiabatic passage, laser-molecule interaction

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Authors: Perla Elizabeth Jimarez Rocha, Carolina Daniela Tejeda Franco, Arturo Minor Martínez, Annel Gomez Coello

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One of the biggest problems in developing new therapies for the management and treatment of voice disorders is the difficulty of objectively evaluating the results of each treatment. A system was proposed that captures and records voice signals, in addition to analyzing the vocal quality (fundamental frequency, zero crossings, energy, and amplitude spectrum), as well as the subglottic pressure (cm H2O) during the sustained phonation of the vowel / a /; a recording system is implemented, as well as an interactive system that records information on subglottic pressure. In Mexico City, a control group of 31 patients with phoniatric pathology is proposed; non-invasive tests were performed for these most common vocal pathologies (Nodules, Polyps, Irritative Laryngitis, Ventricular Dysphonia, Laryngeal Cancer, Dysphonia, and Dysphagia). The most common pathology was irritative laryngitis (32%), followed by vocal fold paralysis (unilateral and bilateral,19.4 %). We take into consideration men and women in the pathological groups due to the physiological difference. They were separated in gender by the difference in the morphology of the respiratory tract.

Keywords: amplitude spectrum, energy, fundamental frequency, subglottic pressure, zero crossings

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Authors: H. Bhuyan, S. Mändl, M. Favre, M. Cisternas, A. Henriquez, E. Wyndham, M. Walczak, D. Manova

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The 470 Li-24 Cr and 460Li-21 Cr are two alloys belonging to the next generation of super-ferritic nickel free stainless steel grades, containing titanium (Ti), niobium (Nb) and small percentage of carbon (C) and nitrogen (N). The addition of Ti and Nb improves in general the corrosion resistance while the low interstitial content of C and N assures finer precipitates and greater ductility compared to conventional ferritic grades. These grades are considered an economic alternative to AISI 316L and 304 due to comparable or superior corrosion. However, since 316L and 304 can be nitrided to improve the mechanical surface properties like hardness and wear; it is hypothesize that the tribological properties of these super-ferritic stainless steels grades can also be improved by plasma nitriding. Thus two sets of plasma immersion ion implantation experiments have been carried out, one with a high pressure capacitively coupled radio frequency plasma at PUC Chile and the other using a low pressure microwave plasma at IOM Leipzig, in order to explore further improvements in the mechanical properties of 470 Li-24 Cr and 460Li-21 Cr steel. Nitrided and unnitrided substrates have been subsequently investigated using different surface characterization techniques including secondary ion mass spectroscopy, scanning electron microscopy, energy dispersive x-ray analysis, Vickers hardness, wear resistance, as well as corrosion test. In most of the characterizations no major differences have been observed for nitrided 470 Li-24 Cr and 460Li-21 Cr. Due to the ion bombardment, an increase in the surface roughness is observed for higher treatment temperature, independent of the steel types. The formation of chromium nitride compound takes place only at a treatment temperature around 4000C-4500C, or above. However, corrosion properties deteriorate after treatment at higher temperatures. The physical characterization results show up to 25 at.% of nitrogen for a diffusion zone of 4-6 m, and a 4-5 times increase in hardness for different experimental conditions. The samples implanted with temperature higher than 400 °C presented a wear resistance around two orders of magnitude higher than the untreated substrates. The hardness is apparently affected by the different roughness of the samples and their different profile of nitrogen.

Keywords: ion implantation, plasma, RF and microwave plasma, stainless steel

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Authors: Surjyakanta Rana, Sreekantha B. Jonnalagadda

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Synthesis of well distributed Pd nanoparticles (3 – 7 nm) on organo amine-functionalized graphene is reported, which demonstrated excellent catalytic activity towards Suzuki coupling reaction. The active material was characterized by X-ray diffraction (XRD), BET surface area, X-ray photoelectron spectra (XPS), Fourier-transfer infrared spectroscopy (FTIR), Raman spectra, Scanning electron microscope (SEM), Transmittance electron microscopy (TEM) analysis and HRTEM. FT-IR revealed that the organic amine functional group was successfully grafted onto the graphene oxide surface. The formation of palladium nanoparticles was confirmed by XPS, TEM and HRTEM techniques. The catalytic activity in the coupling reaction was superb with 100% conversion and 98 % yield and also activity remained almost unaltered up to six cycles. Typically, an extremely high turnover frequency of 185,078 h-1 is observed in the C-C Suzuki coupling reaction using organo di-amine functionalized graphene as catalyst.

Keywords: Di-amine, graphene, Pd nanoparticle, suzuki coupling

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Authors: Conceição, J. F. M., Rebelo H., Corneliu C., Pereira L.

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This research analyses the response of two distinct types of concrete blocks, each possessing an approximate unconfined compressive strength of 30MPa, when exposed to high-velocity impacts produced by an Explosively Formed Penetrator (EFP) traveling at an initial velocity of 1200 m/s. Given the scarcity of studies exploring high-velocity impacts on concrete, the primary aim of this research is to scrutinize how concrete behaves under high-speed impacts, ultimately contributing valuable insights to the development of protective structures. To achieve this objective, a comprehensive numerical analysis was carried out in LS-DYNA to delve into the fracture mechanisms inherent in concrete under such extreme conditions. Subsequently, the obtained numerical outcomes were compared and validated through eight experimental field tests. The methodology employed involved a robust combination of numerical simulations and real-world experiments, ensuring a comprehensive understanding of concrete behavior in scenarios involving rapid, high-energy impacts.

Keywords: high-velocity, impact, numerical analysis, experimental tests, concrete

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Authors: R. M. Bashir, Sabo Elizabeth

Abstract:

Electronic learning is an increasingly popular learning approach in higher educational institutions due to vast growth of internet technology. An investigation on the assessment of e-learning facilities and information need by open and distance learning students in Jalingo, Nigeria was conducted. Structured questionnaires were administered to 70 students of the university. Information sourced from the respondents covered demographic, economic and institutional variables. Data collected for demographic variables were computed as frequency count and percentages. Information on assessment of e-learning facilities and information need among open and distance learning students was computed on a three or four point Likert Rating Scale. Findings indicated that there are more men compared to women, a large proportion of the respondents are married and there are more matured students. A high proportion of the students obtained qualifications higher than the secondary school certificate. The proportion of computer literate students was higher compared with those students that owned a computer. Inadequate e-books and reference materials, internet gadgets and inadequate books (hard copies) and reference material are factors that limit utilization of e-learning facilities. Inadequate computer facilities caused delay in examination schedule at the study center. Open and distance learning students required to a high extent information on university timetable and schedule of activities, books (hard and e-books) and reference materials and contact with course coordinators via internet for better learning and academic performance.

Keywords: open and distance learning, information required, electronic books, internet gadgets, Likert scale test

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Authors: Fares A. Mayia, Mahmoud A. Yamany, Mushabbab A. Asiri

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In recent years, non-invasive Focused Ultrasound (FU) has been utilized for generating bubbles (cavities) to ablate target tissue by mechanical fractionation. Intensities >10 kW/cm² are required to generate the inertial cavities. The generation, rapid growth, and collapse of these inertial cavities cause tissue fractionation and the process is called Histotripsy. The ability to fractionate tissue from outside the body has many clinical applications including the destruction of the tumor mass. The process of tissue fractionation leaves a void at the treated site, where all the affected tissue is liquefied to particles at sub-micron size. The liquefied tissue will eventually be absorbed by the body. Histotripsy is a promising non-invasive treatment modality. This paper presents a technique for generating inertial cavities at lower intensities (< 1 kW/cm²). The technique (patent pending) is based on amplitude modulation (AM), whereby a low frequency signal modulates the amplitude of a higher frequency FU wave. Cavitation threshold is lower at low frequencies; the intensity required to generate cavitation in water at 10 kHz is two orders of magnitude lower than the intensity at 1 MHz. The Amplitude Modulation technique can operate in both continuous wave (CW) and pulse wave (PW) modes, and the percentage modulation (modulation index) can be varied from 0 % (thermal effect) to 100 % (cavitation effect), thus allowing a range of ablating effects from Hyperthermia to Histotripsy. Furthermore, changing the frequency of the modulating signal allows controlling the size of the generated cavities. Results from in vitro work demonstrate the efficacy of the new technique in fractionating soft tissue and solid calcium carbonate (Chalk) material. The technique, when combined with MR or Ultrasound imaging, will present a precise treatment modality for ablating diseased tissue without affecting the surrounding healthy tissue.

Keywords: focused ultrasound therapy, histotripsy, inertial cavitation, mechanical tissue ablation

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Authors: Tamal Sur, Tapas Acharya

Abstract:

Identifying the water resource in hard crystalline rock terrain has been a huge challenge over the decades as it is considered a poor groundwater province area. Over the years, usage of satellite imagery for the delineation of groundwater potential zone in sheared hard rock terrain has been occasionally successful. In numerous circumstances, it has been observed that groundwater potential zone delineated by satellite imagery study has failed to yield satisfactory result on its own. The present study discusses the fact that zones having a high concentration of lineaments oblique to the general trend of shear fabric could be good groundwater potential zones within a shear zone in crystalline fractured rock aquifer system. Due to this fact, the density of lineaments and the number of intersecting lineaments increases over that particular region, making it a suitable locale for good groundwater recharge, which is mostly composed of Precambrian metamorphic rocks i.e., quartzite, granite gneisses, porphyroclastic granite-gneiss, quartzo-feldspathic-granite-gneiss, mylonitic granites, quartz-biotite-granite gneiss and some phyllites of Purulia district of West Bengal, NE India. This study aims to construct an attempt to demonstrate the relationship of the high amount of lineament accumulation and their intersection with high groundwater fluctuation zones, i.e., good groundwater potential zones. On the basis of that, an effort has been made to characterize the shear zones with respect to their groundwater potentiality. Satellite imagery data (IRS-P6 LISS IV standard FCC image) analysis reveals the bifurcating nature of North Purulia shear zone (NPSZ) and South Purulia shear zone (SPSZ) over the study area. Careful analysis of lineament rose diagrams, lineament density map, lineament intersection density map, and frequency diagrams for water table depths with an emphasis on high water table fluctuations exhibit the fact that different structural features existing over North and South Purulia shear zones can affect the nature of hydraulic potential of that region.

Keywords: crystalline hard rock terrain, groundwater recharge, hydrogeology, lineaments, shear zone, water table fluctuation

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Authors: Thapthep Paprach, Benya Lertsuwan

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Investment fraud is not a new criminal, but there are still more victims during the Internet of Things era. This kind of criminal has been classified as a national and transnational financial crime problem all over the world. In Thailand, the country has also been attacked by this kind of crime. This research concerns whether the mass media that is supposed to cover news about online investment scams realized and warned Thais about this crime. Thus, this study explores the value of news about investment fraud in terms of frequency. The methodology uses web crawling from the top 5 news agency websites that have the most access. We pull out all information reporting about investment fraud. The findings revealed that the ‘Khaosod’ news agency was the first rank in reporting on investment crime. On the other hand, ‘Matichon’ was the least reported. Thairat news agencies frequently reported such criminals from midnight to very early in the morning, while other news agencies reported during the daytime. The results between the frequency of news reporting about investment fraud and the monthly number of victim reports are not correlated. Although the most cases reported to Thai police were in February 2023, but the most news reported was in January 2023. In conclusion, there might be a negative correlation between the amount of investment fraud news reported and the number of victims.

Keywords: investment fraud, news value, online news report, Ponzi schemes, Romance scam

Procedia PDF Downloads 73

Authors: Tamal Sur, Tapas Acharya

Abstract:

Identifying the water resource in hard crystalline rock terrain has been a huge challenge over the decades as it is considered a poor groundwater province area. Over the years, usage of satellite imagery for the delineation of groundwater potential zone in sheared hard rock terrain has been occasionally successful. In numerous circumstances, it has been observed that groundwater potential zone delineated by satellite imagery study has failed to yield satisfactory result on its own. The present study discusses the fact that zones having high concentration of lineaments oblique to the general trend of shear fabric could be good groundwater potential zones within a shear zone in crystalline fractured rock aquifer system. Due to this fact, the density of lineaments and the number of intersecting lineaments increases over that particular region, making it a suitable locale for good groundwater recharge, which is mostly composed of Precambrian metamorphic rocks i.e., quartzite, granite gneisses, porphyroclastic granite-gneiss, quartzo-feldspathic-granite-gneiss, mylonitic granites, quartz-biotite-granite gneiss and some phyllites of Purulia district of West Bengal, NE India. This study aims to construct an attempt to demonstrate the relationship of high amount of lineament accumulation and their intersection with high groundwater fluctuation zones i.e., good groundwater potential zones. On the basis of that, an effort has been made to characterize the shear zones with respect to their groundwater potentiality. Satellite imagery data (IRS-P6 LISS IV standard FCC image) analysis reveals the bifurcating nature of North Purulia shear zone (NPSZ) and South Purulia shear zone (SPSZ) over the study area. Careful analysis of lineament rose diagrams, lineament density map, lineament intersection density map, and frequency diagrams for water table depths with an emphasis on high water table fluctuations exhibit the fact that different structural features existing over North and South Purulia shear zones can affect the nature of hydraulic potential of that region.

Keywords: crystalline hard rock terrain, groundwater recharge, hydrogeology, lineaments, shear zone, water table fluctuation

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Authors: Seyed Saeid Tabaee, Mohammad Afshari, Bahador Ziaeemehr, Omid Bahar

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Nowadays, using modern structural systems with specific capabilities, like Diagrid, is emerging around the world. In this paper, a new resisting system, a combination of both Diagrid axial behavior and proper seismic performance of regular moment frames in tall buildings, named 'Hybrid Diagrid' is presented. The scaled specimen of the suggested hybrid system was built and tested using IIEES shaking table. The natural frequency and structural response of the analytical model were updated with the real experimental results. In order to compare its performance with the traditional Diagrid and moment frame systems, time history analysis was carried out. Extensive analysis shows the efficient seismic responses and economical behavior of Hybrid Diagrid structure with respect to the other two systems.

Keywords: hybrid diagrid system, moment frame, shaking table, tall buildings, time history analysis

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Authors: Mapatsakon Sarapat, Mongkol Ketwongsa, Somchat Sonasang, Preecha Yupapin

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The designed and performed preliminary tests on a space-time control circuit using a two-level system circuit with a 4-5 cm diameter microstrip for realistic teleportation have been demonstrated. It begins by calculating the parameters that allow a circuit that uses the alternative current (AC) at a specified frequency as the input signal. A method that causes electrons to move along the circuit perimeter starting at the speed of light, which found satisfaction based on the wave-particle duality. It is able to establish the supersonic speed (faster than light) for the electron cloud in the middle of the circuit, creating a timeline and propulsive force as well. The timeline is formed by the stretching and shrinking time cancellation in the relativistic regime, in which the absolute time has vanished. In fact, both black holes and white holes are created from time signals at the beginning, where the speed of electrons travels close to the speed of light. They entangle together like a capsule until they reach the point where they collapse and cancel each other out, which is controlled by the frequency of the circuit. Therefore, we can apply this method to large-scale circuits such as potassium, from which the same method can be applied to form the system to teleport living things. In fact, the black hole is a hibernation system environment that allows living things to live and travel to the destination of teleportation, which can be controlled from position and time relative to the speed of light. When the capsule reaches its destination, it increases the frequency of the black holes and white holes canceling each other out to a balanced environment. Therefore, life can safely teleport to the destination. Therefore, there must be the same system at the origin and destination, which could be a network. Moreover, it can also be applied to space travel as well. The design system will be tested on a small system using a microstrip circuit system that we can create in the laboratory on a limited budget that can be used in both wired and wireless systems.

Keywords: quantum teleportation, black-white hole, time, timeline, relativistic electronics

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Authors: G. Peker, Tolga N. Aynur, E. Tinar

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In order to determine the energy consumption level and cooling characteristics of a domestic refrigerator controlled with various cooling system algorithms, a side by side type (SBS) refrigerator was tested in temperature and humidity controlled chamber conditions. Two different control algorithms; so-called drop-in and frequency controlled variable capacity compressor algorithms, were tested on the same refrigerator. Refrigerator cooling characteristics were investigated for both cases and results were compared with each other. The most important comparison parameters between the two algorithms were taken as; temperature distribution, energy consumption, evaporation and condensation temperatures, and refrigerator run times. Standard energy consumption tests were carried out on the same appliance and resulted in almost the same energy consumption levels, with a difference of %1,5. By using these two different control algorithms, the power consumptions character/profile of the refrigerator was found to be similar. By following the associated energy measurement standard, the temperature values of the test packages were measured to be slightly higher for the frequency controlled algorithm compared to the drop-in algorithm. This paper contains the details of this experimental study conducted with different cooling control algorithms and compares the findings based on the same standard conditions.

Keywords: control algorithm, cooling, energy consumption, refrigerator

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Authors: Baghdasaryan Marinka

Abstract:

The operation modes of the synchronous motors used in the production processes are greatly conditioned by the accidentally changing technological and power indices.  As a result, the electrical drive synchronous motor may appear in irregular operation regimes. Although there are numerous works devoted to the development of the regulator for the synchronous motor operation modes, their application for the motors working in the irregular modes is not expedient. In this work, to estimate the issues concerning the stability of the synchronous electrical drive system, the transfer functions of the electrical drive synchronous motors operating in the synchronous and induction modes have been obtained.  For that purpose, a model for investigating the frequency characteristics has been developed in the LabView environment. Frequency characteristics for assessing the transient process of the electrical drive system, operating in the synchronous and induction modes have been obtained, and based on their assessment, a regulator for improving the operation modes of the motor has been proposed. The proposed regulator can be successfully used to prevent the irregular modes of the electrical drive synchronous motor, as well as to estimate the operation state of the drive motor of the mechanism with a changing load.

Keywords: electrical drive system, synchronous motor, regulator, stability, transition process

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Authors: Sopida Vacharasukpo, Sudarat Khwan-On

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This paper proposes a high step-up DC-DC converter topology for renewable energy system applications. The proposed converter employs only a single power switch instead of using several switches. Compared to the conventional DC-DC step-up converters the higher voltage gain with small output ripples can be achieved by using the proposed high step-up DC-DC converter topology. It can step up the low input voltage (20-50Vdc) generated from the photovoltaic modules to the high output voltage level approximately 600Vdc in order to supply the three-phase inverter fed the three-phase motor drive. In this paper, the operating principle of the proposed converter topology and its control strategy under the continuous conduction mode (CCM) are described. Finally, simulation results are shown to demonstrate the effectiveness of the proposed high step-up DC-DC converter with its control strategy to increase the voltage step-up conversion ratio.

Keywords: DC-DC converter, high step-up ratio, renewable energy, single switch

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Authors: J. Martin, A. Nominé, T. Czerwiec, G. Henrion, T. Belmonte

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The plasma electrolytic oxidation (PEO) is a particular electrochemical process to produce protective oxide ceramic coatings on light-weight metals (Al, Mg, Ti). When applied to aluminum alloys, the resulting PEO coating exhibit improved wear and corrosion resistance because thick, hard, compact and adherent crystalline alumina layers can be achieved. Several investigations have been carried out to improve the efficiency of the PEO process and one particular way consists in tuning the suitable electrical regime. Despite the considerable interest in this process, there is still no clear understanding of the underlying discharge mechanisms that make possible metal oxidation up to hundreds of µm through the ceramic layer. A key parameter that governs the PEO process is the numerous short-lived micro-discharges (micro-plasma in liquid) that occur continuously over the processed surface when the high applied voltage exceeds the critical dielectric breakdown value of the growing ceramic layer. By using a bipolar pulsed current to supply the electrodes, we previously observed that micro-discharges are delayed with respect to the rising edge of the anodic current. Nevertheless, explanation of the origin of such phenomena is still not clear and needs more systematic investigations. The aim of the present communication is to identify the relationship that exists between this delay and the mechanisms responsible of the oxide growth. For this purpose, the delay of micro-discharges ignition is investigated as the function of various electrical parameters such as the current density (J), the current pulse frequency (F) and the anodic to cathodic charge quantity ratio (R = Qp/Qn) delivered to the electrodes. The PEO process was conducted on Al2214 aluminum alloy substrates in a solution containing potassium hydroxide [KOH] and sodium silicate diluted in deionized water. The light emitted from micro-discharges was detected by a photomultiplier and the micro-discharge parameters (number, size, life-time) were measured during the process by means of ultra-fast video imaging (125 kfr./s). SEM observations and roughness measurements were performed to characterize the morphology of the elaborated oxide coatings while XRD was carried out to evaluate the amount of corundum -Al203 phase. Results show that whatever the applied current waveform, the delay of micro-discharge appearance increases as the process goes on. Moreover, the delay is shorter when the current density J (A/dm2), the current pulse frequency F (Hz) and the ratio of charge quantity R are high. It also appears that shorter delays are associated to stronger micro-discharges (localized, long and large micro-discharges) which have a detrimental effect on the elaborated oxide layers (thin and porous). On the basis of the results, a model for the growth of the PEO oxide layers will be presented and discussed. Experimental results support that a mechanism of electrical charge accumulation at the oxide surface / electrolyte interface takes place until the dielectric breakdown occurs and thus until micro-discharges appear.

Keywords: aluminium, micro-discharges, oxidation mechanisms, plasma electrolytic oxidation

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Authors: Quang Minh Dinh, Jian Guang Qin, Sabine Dittmann, Dinh Dac Tran

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The age and population structure the dermal gopy Parapocryptes serperaster were studied using length distributions, otolith and von Bertalanffy model in the Mekong Delta over a whole year through monthly sampling. The sex ratio of P. serperaster was near 1:1, and von Bertalanffy growth parameters were L∞= 25.2 cm, K = 0.74 yr-1, and t0 = -0.22 yr-1. Fish size at first entry to fishery was 14.6 cm, and fishing mortality (1.57 yr-1) and natural mortality (1.51 yr-1) accounted for 51% and 49% of the total mortality (3.07 yr-1), respectively. Relative yield-per-recruit and biomass-per-recruit analyses revealed the levels of maximum exploitation yield (Emax = 0.83), maximum economic yield (E0.1 = 0.71) and the yield at 50% reduction of exploitation (E0.5 = 0.37). Otoliths from 164 female and 196 male gobies were readable, and the otolith morphometry data were used for age identification. The mean age estimated by reading otolith annual rings and by analysing length frequency distribution was consistent. This study shows that the otolith morphometry is a reliable method for aging this goby and possibly also applicable for other tropical gobies. The fishery analysis indicates that this goby stock has not been overexploited in the Mekong Delta.

Keywords: Parapcryptes serperaster, otolith, age, pulation structure, Vietnam

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Authors: Moustafa Ibrahim Moustafa

Abstract:

The purpose of this study was to determine the immediate and long term effects of a multimodal program, with the addition of cervical sagittal curve restoration and forward head correction, on severity of dizziness, disability, frequency of dizziness, and severity of cervical pain. 72 patients with cervicogenic dizziness, definite hypolordotic cervical spine, and forward head posture were randomized to experimental or a control group. Both groups received the multimodal program, additionally, the study group received the Denneroll cervical traction. All outcome measures were measured at three intervals. The general linear model indicated a significant group × time effects in favor of experimental group on measures of anterior head translation (F=329.4 P < .0005), cervical lordosis (F=293.7 P < .0005), severity of dizziness (F=262.1 P < .0005), disability (F=248.9 P < .0005), frequency of dizziness (F=53.9 P < .0005), and severity of cervical pain (F=350.1 P < .0005). The addition of Dennroll cervical traction to a multimodal program can positively affect dizziness management outcomes.

Keywords: randomized controlled trial, traction, dizziness, cervical

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Authors: Bing Li, Tong Lu, Lei Qiang

Abstract:

Stoneley waves are interface waves that propagate at the interface between two solid media. In this study, the dispersion characteristics and wave structures of Stoneley waves in elastic multilayered plates are displayed and investigated. With a perspective of bulk wave, a reasonable assumption of the potential function forms of the expansion wave and shear wave in nth layer medium is adopted, and the characteristic equation of Stoneley waves in a three-layered plate is given in a determinant form. The dispersion curves and wave structures are solved and presented in both numerical and simulation results. It is observed that two Stoneley wave modes exist in a three-layered plate, that conspicuous dispersion occurs on low frequency band, that the velocity of each Stoneley wave mode approaches the corresponding Stoneley wave velocity at interface between two half infinite spaces. The wave structures reveal that the in-plane displacement of Stoneley waves are relatively high at interfaces, which shows great potential for interface defects detection.

Keywords: characteristic equation, interface waves, potential function, Stoneley waves, wave structure

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Authors: Meng-Chyi Wu, Bonn Lin, Jyun-Hao Liao, Chein-Ju Chen, Yu-Cheng Jhuang, Mau-Phon Houng, Fang-Hsing Wang, Min-Chu Liu, Cheng-Fu Yang, Cheng-Shong Hong

Abstract:

Since the use of wireless communications has become critical nowadays, the available RF spectrum has become limited. Ultraviolet (UV) communication system can alleviate the spectrum constraint making UV communication system a potential alternative to future communication demands. Also, UV links can provide faster communication rate and can be used in combination with existing RF communication links, providing new communications diversity with higher user capacity. The UV region of electromagnetic spectrum has been of interest to detector, imaging and communication technologies because the stratospheric ozone layer effectively absorbs some solar UV radiation from reaching the earth surface. The wavebands where most of UV radiation is absorbed by the ozone are commonly known as the solar blind region. By operating in UV-C band (200-280 nm) the communication system can minimize the transmission power consumption since it will have less radiation noise. UV communication uses the UV ray as the medium. Electric signal is carried on this band after being modulated and then be transmitted within the atmosphere as channel. Though the background noise of UV-C communication is very low owing to the solar-blind feature, it leads to a large propagation loss. The 370 nm UV provides a much lower propagation loss than that the UV-C does and the recent device technology for UV source on this band is more mature. The fabricated 370 nm AlGaN light-emitting diodes (LEDs) with an aperture size of 45 m exhibit a modulation bandwidth of 165 MHz at 30 mA and a high power of 7 W/cm2 at 230 A/cm2. In order to solve the problem of low power in single UV LED, a UV LED array is presented in.

Keywords: ultraviolet (UV) communication, light-emitting diodes (LEDs), modulation bandwidth, LED array, 370 nm

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Authors: Nassima Behidj-Benyounes, Thoraya Dahmene, Nadjiba Chebout

Abstract:

This work examines the study of the antimicrobrial effect of alkaloids extracted from the seeds of Peganum harmala L (Zygophyllaceae). This natural substance is extracted by using different solvents (aqueous, ethanolic, and hexane). The evaluation of the antimicrobial activity has only dealt with alkaloids. The antimicrobial effect of alkaloids is evaluated on several microorganisms. It has been tested on eight bacterial strains. The extract has been studied by using two yeasts. Finally, three molds have been studied. It should be noted that these agents are characterized by a high frequency of contamination and pathogenicity. Through this study, we note that Staphylococcus aureus, Saccharomyces cerievisae and E. coli are very sensitive in respect of the ethanol extract. Pseudomonas aerogenosa and Penicillium sp. are resistant to this extract. The other microorganisms are moderately sensitive. The study of the antimicrobial activity of different extracts of the Harmel has shown an optimal activity with the ethanol extract.

Keywords: Peganum harmala L., seeds, alkaloids, bacteria, fungi, yeast, antimicrobial activity

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Authors: I. Kurashvili, G. Darsavelidze, T. Kimeridze, G. Chubinidze, I. Tabatadze

Abstract:

At present, a number of modern semiconductor devices based on SiGe alloys have been created in which the latest achievements of high technologies are used. These devices might cause significant changes to networking, computing, and space technology. In the nearest future new materials based on SiGe will be able to restrict the A³B⁵ and Si technologies and firmly establish themselves in medium frequency electronics. Effective realization of these prospects requires the solution of prediction and controlling of structural state and dynamical physical –mechanical properties of new SiGe materials. Based on these circumstances, a complex investigation of structural defects and structural-sensitive dynamic mechanical characteristics of SiGe alloys under different external impacts (deformation, radiation, thermal cycling) acquires great importance. Internal friction (IF) and shear modulus temperature and amplitude dependences of the monocrystalline boron-doped Si_1-xGe_x(x≤0.05) alloys grown by Czochralski technique is studied in initial and ⁶⁰Co gamma-irradiated states. In the initial samples, a set of dislocation origin relaxation processes and accompanying modulus defects are revealed in a temperature interval of 400-800 ⁰C. It is shown that after gamma-irradiation intensity of relaxation internal friction in the vicinity of 280 ⁰C increases and simultaneously activation parameters of high temperature relaxation processes reveal clear rising. It is proposed that these changes of dynamical mechanical characteristics might be caused by a decrease of the dislocation mobility in the Cottrell atmosphere enriched by the radiation defects.

Keywords: internal friction, shear modulus, gamma-irradiation, SiGe alloys

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Authors: Anik Sarminingsih, Krishna V. Pradana

Abstract:

The failure of flood control system can be caused by various factors, such as not considering the uncertainty of designed flood causing the capacity of the flood control system is exceeded. The presence of the uncertainty factor is recognized as a serious issue in hydrological studies. Uncertainty in hydrological analysis is influenced by many factors, starting from reading water elevation data, rainfall data, selection of method of analysis, etc. In hydrological modeling selection of models and parameters corresponding to the watershed conditions should be evaluated by the hydraulic model in the river as a drainage channel. River cross-section capacity is the first defense in knowing the reliability of the flood control system. Reliability of river capacity describes the potential magnitude of flood risk. Case study in this research is Wulan River in Central Java. This river occurring flood almost every year despite some efforts to control floods such as levee, floodway and diversion. The flood-affected areas include several sub-districts, mainly in Kabupaten Kudus and Kabupaten Demak. First step is analyze the frequency of discharge observation from Klambu weir which have time series data from 1951-2013. Frequency analysis is performed using several distribution frequency models such as Gumbel distribution, Normal, Normal Log, Pearson Type III and Log Pearson. The result of the model based on standard deviation overlaps, so the maximum flood discharge from the lower return periods may be worth more than the average discharge for larger return periods. The next step is to perform a hydraulic analysis to evaluate the reliability of river capacity based on the flood discharge resulted from several methods. The selection of the design flood discharge of flood control system is the result of the method closest to bankfull capacity of the river.

Keywords: design flood, hydrological model, reliability, uncertainty, Wulan river

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Authors: Luedech Girdwichai, Witthaya Mekhum, Namthip Kleebbuaban

Abstract:

This research is aimed at studying work efficiency of the supporting staff at Suan Sunandha Rajabhat University by different categories. Supporting staff of Suan Sunandha Rajabhat University consists of government officers, permanent employees, permanent university staff, temporary university staff, and staff of the temporary university employees and government employees, totaling 242. The tools used in this research were questionnaires and data were analyzed by using computer software packages. Statistics includes frequency distribution, percentage, mean and standard deviation. The results showed that the work efficiency of the supporting staff at Suan Sunandha Rajabhat University is high in all areas: flexibility in operation, ability to work with others, productivity and work efficiency, human relations with colleagues and commanders, understanding of the work, and communication with others, the university, colleagues, and commanders.

Keywords: satisfaction, work efficiency, supporting staff, Suan Sunandha Rajabhat University

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Authors: Ali Raad Hassan

Abstract:

In this paper, an (irregular) case relating to base circle, root circle, and pressure angle has been discussed and a computer programme has been developed to simulate and plot spur gear tooth profile, including involute and trochoid curves based on the formulation of rack cutter using different values of pressure angle and profile shift factor and it gave the values of all important geometric parameters. The results showed the flexibility of this approach and versatility of the programme to draw many different cases of spur gear teeth of any module, pressure angle, profile shift factor, number of teeth and rack cutter tip radius. The procedure developed can be extended to produce finite element models of heretofore intractable geometrical forms, to exploring fabrication of nonstandard tooth forms also. Finite elements model of these irregular cases have been built using above programme, and modal analysis has been done using ANSYS software, and natural frequencies of these selected cases have been obtained and discussed.

Keywords: involute, trochoid, pressure angle, profile shift factor, natural frequency

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Authors: Ji Wen Sun, Nan Ping Shen, Yi Bei Wu

Abstract:

This study used Nursing Interventions Classification (NIC-6th) to identify the interventions performed in a pediatric cardiology unit, and then to analysis its frequency, time and difficulty, so as to give a brief review on what our nurses have done. The research team selected a 35 beds pediatric cardiology unit, and drawn all the nursing interventions in the nursing record from our hospital information system (HIS) from 1 October 2015 to 30 November 2015, using NIC-6th to do the matching and then counting their frequencies. Then giving each intervention its own time and difficulty code according to NIC-6th. The results showed that nurses in pediatric cardiology unit performed totally 43 interventions from 5394 statements, and most of them were in RN(basic) education level needed and less than 15 minutes time needed. There still had some interventions just needed by a nursing assistant but done by nurses, which should call for nurse managers to think about the suitable staffing. Thus, counting the summary of the product of frequency, time and difficulty for each intervention of each nurse can know one's performance. Acknowledgement Clinical Management Optimization Project of Shanghai Shen Kang Hospital Development Center (SHDC2014615); Hundred-Talent Program of Construction of Nursing Plateau Discipline (hlgy16073qnhb).

Keywords: nursing interventions, nursing interventions classification, nursing record, pediatric cardiology

Procedia PDF Downloads 359