Thermal Zero Research Articles

Design of MEMS Pressure Sensor Anti-Interference System Based on Filtering and PID Compensation.

Due to the inherent temperature drift and lack of static stability in traditional pressure sensors, which make it difficult for them to meet the increasing demands of various industries, this paper designs a new system. The proposed system integrates temperature measurement and regulation circuits, signal processing, and communication circuits to accurately acquire and transmit pressure sensor data. The system designs a filtering algorithm to filter the original data and develops a data-fitting operation to achieve error compensation of the static characteristics. In order to eliminate the temperature drift problem of the sensor system, the system also adopts an improved PID thermostatic control algorithm to compensate for the temperature drift. Finally, it can also transmit the processed pressure data remotely. The experimental results show that the nonlinear error at 50 °C is reduced from the initial 1.82% to 0.24%; the hysteresis error is significantly reduced from 1.23% to 0.046%; and the repeatability error control is reduced from 3.79% to 0.89%. By compensating for thermal drift, the system's thermal sensitivity drift coefficient is reduced by 74.67%, the thermal zero drift coefficient is reduced by 66.24%, and the wireless communication range is up to 1km. The above significant optimization results fully validate the high accuracy and stability of the system, which is perfectly suited for demanding pressure measurement applications.

MAGNETOHYDRODYNAMIC TERNARY HYBRID NANOFLUID FLOW OVER A STRETCHING SURFACE SUBJECT TO THERMAL CONVECTIVE AND ZERO MASS FLUX CONDITIONS

Nanoparticles have the capability to augment the thermal conductivity of nanofluids. For the transmission of heat, the material’s low thermal conductivity is the key problem. Therefore, to increase the thermal conductivity, researchers mixed different nanoparticles in the base fluids. In this field of study, utilizing three different particles is the most recent strategy to form a ternary hybrid nanofluid that gives us better results in terms of heat transfer. The interaction of three different kinds of nanoparticles, i.e. copper, alumina and silver, is considered with water serving as the base fluid to form a ternary hybrid nanofluid. The paper explores the behavior of ternary hybrid nanofluids on heat and mass transportation phenomena of the two-dimensional magnetohydrodynamic (MHD) micropolar flow across a porous extending surface with zero mass flux and convective conditions. The Brownian motion, thermal radiation, heat source and sink, and joule heating are taken into consideration in the temperature equation. The chemical reaction is incorporated into the concentration equation. Appropriate similarity transformations are used to transform the system of partial differential equations (PDEs) to a coupled system of ordinary differential equations (ODEs). The homotopy analysis method (HAM) is used to solve the system of the flow equations. The effects of the nanoparticle’s volume fractions and other different physical parameters on the surface drag force, Nusselt number, velocities, microrotation, temperature and concentration profiles are scrutinized through figures and tables. The outcomes of the present investigation show that the heat transfer rate is augmented with the increasing value of thermophoresis parameter. The magnetic field has augmented temperature while the opposite result is seen in velocity and microrotation profiles. With the escalating values of thermophoresis parameter, the concentration and temperature of ternary hybrid nanofluids are boosted while the increasing Brownian and chemical reaction parameters have decreased the concentration profile. The surface friction coefficient exhibited by the ternary hybrid nanofluid is higher than hybrid and conventional nanofluids.

Treatment of brackish water for fossil power plant cooling

In this study, we evaluated the technical, economic and environmental impacts of retrofitting brackish groundwater treatment systems at existing coal- and gas-fired electric generating units (EGUs) to reduce freshwater consumption in wet cooling towers. Based on fleet averages, retrofitting brackish water treatment systems decreases unit freshwater consumption by 94–100%, while increasing the cost of electricity generation by 8–10%. The unit capacity shortfalls are less than 1.1%. The resulting cost of freshwater consumption savings by brackish water treatment is US$1.7 m−3 and US$2.9 m−3 on average for coal- and gas-fired EGUs, respectively. However, these trade-offs are highly affected by the brine disposal method. The use of thermal zero liquid discharge for brine disposal can roughly double the average cost of freshwater consumption savings. The cost-effectiveness of brackish water treatment compared with dry cooling deployment depends on how concentrated brines are managed. The identified trade-offs and their dependence fill knowledge gaps to better inform water management. This study reveals trade-offs in freshwater savings, cost and capacity shortfalls from deploying treated brackish water for wet thermoelectric cooling, as well as its cost-effectiveness, relative to dry cooling retrofit, in saving freshwater.

Research on high temperature performance of pressure sensor

This work proposes a molybdenum (Mo) based pressure sensor capable of operating at temperatures higher than 300 °C. The sensor utilizes a 30 μm thick rectangular pressure-sensitive film and 2 μm thick gate Mo resistors to form a Wheatstone bridge structure to enhance pressure sensing. Finite element analysis (FEA) has been performed to design the sensor and analyze the pressure and temperature effect. The developed sensor with the excitation of 1 V voltage exhibits excellent performance characteristics at room temperature (25 °C), including a sensitivity of 0.05689 mV V−1 kPa−1, 0.15% full scale (FS) accuracy, a nonlinearity of 0.79% FS, and 0.02% FS repeatability. The thermal zero shift of −0.13% FS/°C is obtained in the 25 °C to 300 °C temperature range. The simulation findings illustrate that the thermal mismatch weakens the thermal zero shift by +0.012‰ FS/°C, while the deviation of the temperature coefficient of resistance (TCR) and initial resistivity () aggravate the thermal zero shift by −0.139% FS/°C. Among both, the deviation of and TCR is the major contributor to thermal zero shift. Moreover, it was found that the Seebeck effect caused by the on-chip temperature gradient also affects the accuracy of the sensor. A temperature difference of 5.4 °C produces a thermoelectric potential of 37.95 μV equivalent to a pressure of 670 Pa loading on the chip. Besides, the response characteristics of the sensor at different temperature rates were investigated.

Investigation on the temperature coefficient of frequency performance of LiNbO3 on quartz and glass surface acoustic wave resonators

High impedance ratio (Z-ratio), low temperature coefficient of frequency (TCF) and spurious free characteristic are three main requirements for surface acoustic wave (SAW) resonators. The reported LiTaO3/Quartz (Qz) hetero acoustic layer (HAL) resonator can satisfy them, but the bandwidth is too narrow. LiNbO3 (LN) is suitable for wideband resonators, but the TCF is too large due to its high coupling factor. In this work, we study wideband HAL SAW resonators combining LN and three kinds of substrates with positive TCF and small coefficient of thermal expansion, including Qz, ABC-G and ZERO glasses. By simulation, the Euler angles of (0°, 101°, 0°) for LN, (0°, 160°, 90°) for Qz, and the 0.1–0.2λ (λ is the wavelength) LN thickness are used. Results show LN/Qz, LN/ABC-G and LN/ZERO exhibit Z-ratio of 82.7 dB, 76.2 dB and 76.2 dB, respectively. LN/ABC-G shows the lowest TCF of −61 ppm C−1 at resonance frequency and −62 ppm C−1 at anti-resonance frequency.

Observation of second sound in graphite over 200\u2009K

Second sound refers to the phenomenon of heat propagation as temperature waves in the phonon hydrodynamic transport regime. We directly observe second sound in graphite at temperatures of over 200 K using a sub-picosecond transient grating technique. The experimentally determined dispersion relation of the thermal-wave velocity increases with decreasing grating period, consistent with first-principles-based solution of the Peierls-Boltzmann transport equation. Through simulation, we reveal this increase as a result of thermal zero sound—the thermal waves due to ballistic phonons. Our experimental findings are well explained with the interplay among three groups of phonons: ballistic, diffusive, and hydrodynamic phonons. Our ab initio calculations further predict a large isotope effect on the properties of thermal waves and the existence of second sound at room temperature in isotopically pure graphite.

Energy transport analysis in flow of Carreau nanofluid inspired by variable thermal conductivity and zero mass flux conditions

The presence of nanometric particles in the base fluids lead to form nanofluids. Nanofluids are prominent due to their astonishing features in thermally conducting flows and in the development of electronic and mechanical devices. Based on these motivations, we have designed our article to investigate the thermal conduction features in the free and forced convection flow of unsteady Carreau nanofluid due to stretching cylinder with the effects of variable magnetic field. Moreover, the transport of thermal energy in the flow is properly examined by including the impacts of variable thermal conductivity and nonuniform heat rise/fall. Furthermore, the transport of solutal energy in the flow of nanofluid is encountered under the influences of activation energy and binary chemical reactions. A momentous feature of this study is to employ the zero-mass flux condition at the wall of the cylinder. A section of this study is proposed for mathematical modelling of the current problem. Moreover, the impacts of involved physical constraints are explored by employing an efficient numerical technique namely bvp4c. The features of all physical constraints on flow, thermal and solutal curves are illustrated in the form of graphs and discussed with reasonable physical arguments in discussion section of the article. The core findings of this study are mentioned in the section of closing remarks. The core upshot of the current study is that the nanoparticles concentration rate of nanofluid depicts ascending trend for escalating values of activation energy constraint. A significant upsurge in the coefficients of skin friction and Nusselt number is detected with an escalation in the constraints of buoyancy and thermophoresis forces, respectively. The references regarding this article are also provided at the end.

Laparoscopic thulium fiber laser partial nephrectomy without thermal ischemia

Background. Laparoscopic partial nephrectomy (LPN) in the treatment of small kidney tumors is widespread, but the operation is associated with warm ischemia, which adversely affects the functional state of the kidney. Research is underway on methods of partial nephrectomy with a reduction of thermal ischemia or zero ischemia. The laser energy is one of the directions in the search for options for LPN. The aim of our work is to improve the LPN using a thulium laser. Materials and methods. From 2017 to 2019 a LPN was performed for 16 patients with small tumors, using the thulium laser with a wavelength of 1.94 ^m. There were men 7 (43.8 %), women — 9 (56.2 %), average age was 51 (39—68) years, average kidney tumor size was 24.9 (15—40) mm. The evaluation of laser resectability on the RENAL scale was carried out using 3D modeling. We used the laparoscopic laser aspirator-irrigator to reduce smoke generation during the procedures. Results. The average time of LPN using a fiber thulium laser was 97.5 (70—131) min. The time for kidney resection was 25.6 (10—40) min. 14 (87.5 %) procedures performed completely without warm ischemia. The average blood loss during surgery was 111.3 (50—250) ml. The duration of postoperative treatment was 7.1 (5—9) days. A positive surgical margin was not observed. Histological examination revealed renal cell carcinoma in 14 (87.5 %) patients, G2 — 10 (71.4 %), G2 — 4 (28.6 %). When examining glomerular filtratoin rare in the operated patients after procedures, no changes were observed. Conclusion. The use of the thulium laser for LPN allows perform the procedure without warm ischemia in selected patients with a predominantly extrarenal tumor location. The use of a laparoscopic instrument the laser aspirator-irrigator with a drip water supply and simultaneous aspiration reduced smoke generation during laser thulium resection, the operation performed under conditions of improved visualization, which prevents the danger of a positive surgical edge. Further monitoring of the results of applying the method of thulium laser LPN is required.

Prediction of annual generations of the tomato leaf miner Tuta absoluta on tomato cultivations in Egypt

BackgroundTomato crop is the first vegetable crop in Egypt; it covers about 3% of Egypt’s total planted area. The tomato leaf miner Tuta absoluta is a polyphagous insect pest which feeds on several solanaceous plant species and preferentially on tomato causing high losses in productivity. This study aims to predict the annual generations and expected times for moth emergence in order to select the best time for the pest management.MethodsSpecimens of T. absoluta were collected from infested tomato field and reared under controlled temperatures to calculate the thermal requirements for development and completing the whole generation. The duration of different developmental stages of this insect and the life table parameters were estimated. The data were used to calculate the thermal constant and developmental zero for different developmental stages using the formula of Jasic (Bihemoslov 72:383-390, 1975) mathit{mathsf{y}}=mathit{mathsf{n}} left(mathit{mathsf{t}}-mathit{mathsf{x}}right) .ResultsEcological studies were performed to evaluate the adverse effects of climatic changes on insect populations based on accumulation of the thermal requirements for development. The developmental zero was 5.79 °C and the thermal constant was 171 DDs to complete the pupal stage development. Based on these values, the pupae development can be repeated 36 times during 2012 when the mean annual temperature was 22.8 °C. In Giza governorate, the average life cycle duration during 2012 was 52.44 days when the mean annual temperature was 22.8 °C, the number of annual generations was 8.05, and the timing of the first generation was 11.66 days in April 2012 while the 8th generation cycle was obtained after 28.2 days of January 2013. In Qena governorate, the mean annual temperature was increased to be 26.04 °C, so the annual generations increased to 9.52. The first generation was recorded by the end of April 2012 while the 9th generation was completed on 24.4 days of December 2012. In Merssa-Matrouh governorate, the mean annual temperature was 20.53 °C and the number of the annual generations was found to be 7 during 2012. The first generation occurred on the day 19.86 of April 2012 while the 7th generation cycle was detected after 30.98 days of January 2013. This means that there must be successive emergence of the adults but with variations during the different months and locations in correlation with variation of temperatures.ConclusionThe accumulated thermal requirements appeared to be a very critical factor affecting insect development to complete the annual generations of T. absoluta in Egypt. This helps in designing the effective program and the best time for the pest management.

Bulk-micromachined, SOI-based half-bridge silicon strain gauges for high pressure applications

This paper presents a new half-bridge silicon strain gauge fabricated on a silicon-on-insulator (SOI) substrate by MEMS bulk-micromachining technology. These gauges have holes etched through the wafer by deep reactive ion etching (DRIE) and a closed shape with four sides, unlike the current competitive devices with open structures. This unique design minimizes the shifting or rotation of gauge position and enhances the bonding strength during glass-frit bonding, leading to an improved sensor performance and yield, and hence, a reduction in sensor cost. The prototype half-bridge gauges were tested under strains ranging from −170 to 170 and were shown to have a linear output with a typical gauge factor of about 112 and an average hysteresis of 0.0192% FS. In addition, the full bridge output for 0–50 bar pressure shows a typical sensitivity of about 0.345 mV/V/bar, a maximum thermal zero shift of −7.33% FS, and a thermal sensitivity shift of −0.17% FS/°C.

Derivative expansion for the electromagnetic Casimir free energy at high temperatures

We study the contribution of the thermal zero modes to the Casimir free energy, in the case of a fluctuating electromagnetic (EM) field in the presence of real materials described by frequency-dependent, local and isotropic permittivity ($\epsilon$) and permeability ($\mu$) functions. Those zero modes, present at any finite temperature, become dominant at high temperatures, since the theory is dimensionally reduced. Our work, within the context of the Derivative Expansion (DE) approach, focusses on the emergence of non analyticities in that dimensionally reduced theory. We conclude that the DE is well defined whenever the function $\Omega(\omega)$, defined by $[\Omega(\omega)]^2 \equiv \omega^2\epsilon(\omega)$, vanishes in the zero-frequency limit, for at least one of the two material media involved.

A surface micromachined pressure sensor based on polysilicon nanofilm piezoresistors

In order to effectively apply the piezoresistive properties of the polysilicon nanofilm and the surface micromachined technology, a surface micromachined pressure sensor based on polysilicon nanofilm piezoresistors and vacuum cavity is presented. The design of the sensor structure is carried out by finite element analysis for improving its performance. Residual stress relaxation in the polysilicon diaphragm and prevention of adhesion in the sensor cavity are carried out in the process of the sensor fabrication. The sensor sample is fabricated according to the structure designed. The sample's measurement results show that a full scale pressure of 2.5MPa, a sensitivity of 2.896×10−2mV/V/kPa at 25°C, an overpressure of 7 times higher than the full scale pressure at 25°C, a thermal zero drift of −0.01%FS/°C and a thermal sensitivity drift of −0.1%FS/°C in a temperature range of −40 to 200°C are achieved. The measurement performance is excellent and agrees with the predictions of the design method.

Conditions of resonance interaction of acoustic periodic waves interaction

We consider differential equations of gas dynamics, when the thermal conductivity and viscosity coefficients equal zero. The system is supplemented with equations of state for the gas pressure and the total energy; these equations do not depend on the properties of gas, i.e. are of a general form. We construct asymptotical approximation for the resonance interaction of acoustic periodic waves, which is uniformly valid in the long time interval. A system coefficient allows determining the resonance occurring condition the relation between gas pressure and temperature at the initial time. We investigate the ideal and non-ideal gas and determine the relationship between the parameters, which causes the of resonanse vanishing in non-ideal gas.

Detection H2S mixed with natural gas using hollow-core photonic bandgap fiber

An optical fiber gas sensor using hollow-core photonic bandgap fiber as a gas cell is proposed to detect H2S mixed with natural gas. This sensor is advantageous for eliminating instability of light source, impact of thermal zero drift, and zero shift of photoelectric device. The gas sensing probe of configuration is using two shorter pieces of hollow-core photonic bandgap fiber (HC-PBF) with the same overall length instead of one long piece of HC-PBF to improve the system response. The experimental dates indicate that a minimum detectivity of 10ppm for the system configuration was estimated.

Temperature Dependence of Zero Point in Force Transducers II: How to Account for the Effects of a Zero Balancing Resistor

On the basis of findings discussed in a companion paper, two novel calculation procedures (iterative and analytic) for force transducer zero balancing without inducing temperature errors in the Wheatstone bridge circuit are introduced. The iterative method calculates a proper temperature compensating resistance without accounting for the effects of a zero balancing resistor and then determines the resistance of a zero balancing resistor. This process is repeated by computing subsequent ancillary resistance pairs until the thermal zero shift is small enough. The analytic solution uses bridge output ratio expressions at two different temperatures in the presence of a temperature compensating resistor and a zero balancing resistor in terms of the output ratios at the two temperatures in the absence of both resistors. It is found that the difference in output ratio between the two temperatures obtained by using the iterative method converges to zero as long as the temperature compensating resistor TCR is greater than the zero balancing resistor TCR. It is also found that the iterative solution is practically equivalent to the analytic solution in that the total resistance of temperature compensating resistors obtained from using the iterative method converges to the temperature compensating resistance calculated using the analytic solution.

The effect of fractional parameter on a perfect conducting elastic half-space in generalized magneto-thermoelasticity

Recently, Sherief et al. (Int. J. Solids Struct. 47:269–275, 2010) proposed a model in generalized thermoelasticity based on the fractional order time derivatives. The propagation of electro-magneto-thermoelastic disturbances in a perfectly conducting elastic half-space is investigated in the context of the above fractional order theory of generalized thermoelasticity. There acts an initial magnetic field parallel to the plane boundary of the half-space. Normal mode analysis together with the eigenvalue approach technique is used to solve the resulting non-dimensional coupled governing equations of the problem. The obtained solution is then applied to two specific problems for the half-space, whose boundary is subjected to (i) thermally isolated surfaces subjected to time-dependent compression and (ii) a time-dependent thermal shock and zero stress. The effects of fractional parameter and magnetic field on the variations of different field quantities inside the half-space are analyzed graphically.

A near‐infrared optical fiber sensor for carbon monoxide concentration monitoring

AbstractAn optical fiber sensor presented is capable of monitoring the presence of carbon monoxide (CO) in the exhaust environment.Conventional gas sensor used to detect CO concentration is often difficult to achieve high sensitivity, selectivity, and specificity in presence of a mixture of gases. The design of this sensor using DFB LD as light source and low‐cost near‐infrared components, which make it suitable for using in an exhaust environment, is discussed. The sensor based on spectrum absorption principle is immune to corrosion and poison as it consists of glass and ceramic parts. By using differential construction, it can eliminate the influence of common mode interfering signals caused by the wave of LDs light intension, thermal zero shift, and zero shift of photoelectric device. A national instrument cRIO‐9215 data acquisition card was used to acquire the output voltages and a LabView virtual instrument was used to store and process data. The response of the sensor to carbon dioxide supplied from the standard gas with dry nitrogen as a balancing gas in the laboratory was performed. The experimental results indicated that the sensor has been developed to operate within an exhaust environment and have high sensitivity and stability so it does not suffer from other gases interferences. The lower limit of detection for the sensor was found to be not less than 50 ppm for CO. This can be meeting the requirement of 100 ppm which is to be poisonous to human. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2192–2195, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25469

Innovative beneficial reuse of reverse osmosis concentrate using bipolar membrane electrodialysis and electrochlorination processes

Reverse osmosis (RO) is a widely used and rapidly growing desalination technology. A major disadvantage of this process is that the concentrate from the RO process, which could be as much as 25% of the feed stream, represents a polluting stream. This waste stream could pose a significant challenge to the implementation of this process, particularly for inland communities which do not have the option of ocean disposal. An excellent environmentally benign approach to disposal could be beneficial reuse of the waste stream. This study presents two innovative beneficial reuse strategies for RO concentrate produced by an integrated membrane system (IMS) from a wastewater reclamation facility. The technologies evaluated in this study included bipolar membrane electrodialysis (BMED) for conversion of RO concentrate into mixed acid and mixed base streams, and electrochlorination (EC) for onsite chlorine generation. Bench-scale studies conducted with BMED demonstrated that RO concentrate could be desalted while producing mixed acids and mixed bases with concentrations as high as 0.2N. Similarly, the EC process was capable of producing a 0.6% hypochlorite solution from RO concentrate. The acids and bases as well as the hypochlorite produced could be directly applied to the RO process as well as upstream pre-treatment processes. A preliminary economic evaluation of the viability of these two approaches was conducted by conducting rough order of magnitude cost estimates based on the bench-scale performance of these processes on RO concentrate. A comparison of the overall costs of an Integrated Membrane System utilizing these innovative reuse strategies with conventional disposal options and thermal zero liquid discharge treatment is presented. This comparison indicates that a reuse approach might be economically viable for inland wastewater reuse facilities that utilize RO membranes and have limited options for concentrate disposal.

Design and Fabrication of a Piezoresistive Pressure Sensor for Ultra High Temperature Environment

In order to solve the pressure measurement problem in the harsh environment, a piezoresistive pressure sensor has been developed, which can be used under high temperature above 200°C and is able to endure instantaneous ultra high temperature (2000°C, duration≦2s) impact. Based on the MEMS (Micro Electro-Mechanical System) and integrated circuit technology, the piezoresistive pressure sensor's sensitive element was fabricated and constituted by silicon substrate, a thin buried silicon dioxide layer, four p-type resistors in the measuring circuit layer by boron ion implantation and photolithography, the top SiO2 layer by oxidation, stress matching Si3N4 layer, and a Ti-Pt-Au beam lead layer for connecting p-type resistors by sputtering. In order to decrease the leak-current influence to sensor in high temperature above 200°C, the buried SiO2 layer with the thickness 367 nm was fabricated by the SIMOX (Separation by Implantation of Oxygen) technology, which was instead of p-n junction to isolate the upper measuring circuit layer from Si substrate. In order to endure instantaneous ultra high temperature impact, the mechanical structure with cantilever & diaphragm and transmitting beam was designed. By laser welding and high temperature packaging technology, the high temperature piezoresistive pressure sensor was fabricated with range of 120MPa. After the thermal compensation, the sensor's thermal zero drift k0 and thermal sensitivity drift ks were easy to be less than 3×10−4FS/°C. The experimental results show that the developed piezoresistive pressure sensor has good performances under high temperature and is able to endure instantaneous ultra high temperature impact, which meets the requirements of modern industry, such as aviation, oil, engine, etc.

A fast response probe system for in-flight measurements of atmospheric turbulence

A fast response probe system for in-flight, three-dimensional measurements of atmospheric turbulence is presented. The system comprises a commercial five-hole probe connected to miniature pressure transducers by extremely short pneumatic lines. This design yields high dynamic response with negligible pneumatic transmission errors at least up to 10 Hz. The transducers are installed into a temperature-conditioned shell to eliminate thermal zero and sensitivity shifts during flight. The system has been tested on the Falcon D-CMET research aircraft of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) in Oberpfaffenhofen at flight altitudes up to 37 000 ft (11 278 m) and Mach numbers up to 0.75. Spectral analyses of the air-data obtained by the system confirm the predictions concerning its high frequency response capabilities. Simultaneous measurements with conventional air sensing devices installed in the aircraft provide evidence regarding the operational reliability and the accuracy of the system.