Complete Operation Cycle Research Articles

Silicon-Based Piezoresistive Stress Sensor Arrays for Use in Flexible Tactile Skin.

Bioinspired robotics and smart prostheses have many applications in the healthcare sector. Patients can use them for rehabilitation or day-to-day assistance, allowing them to regain some agency over their movements. The most common way to make these smart artificial limbs is by adding a "human-like" electronic skin to detect force and emulate touch detection. This paper presents a fully integrated CMOS-based stress sensor design with a high dynamic range (100 kPa to 100 MPa) supported by an adaptive gain-controlled chopping amplifier. The sensor chip includes four identical sensing structures capable of measuring the chip's local stress gradient and complete readout circuitry supporting data transfer via I2C protocol. The sensor takes 10.2 ms to measure through all four structures and goes into a low-power mode when not in use. The designed chip consumes a total current of ∼300 μA for one complete operation cycle and ∼30 μA during low power mode in simulations. Moreover, the complete design is CMOS-based, making it easier for large-scale commercial fabrication and more affordable for patients in the long run. This paper further proposes the concept of a tactile smart skin by integrating a network of sensor chips with flexible polymers.

Sponge iron enriches autotrophic/aerobic denitrifying bacteria to enhance denitrification in sequencing batch reactor

Sponge iron (SFe) coupled with a sludge system has great potential for improving biological denitrification; however, the underlying mechanism is not yet fully understood. In this study, the denitrification performance and microbial characteristics of ordinary sludge and SFe-sludge systems were investigated. Overall, the SFe-sludge reactor had faster ammonium degradation rate (94.0 %) and less nitrate accumulation (1.5–53.3 times lower) than ordinary reactor during the complete operation cycle of sequencing batch reactors. The addition of SFe increased the activities of nitrate and nitrite reductases. The total relative abundance of autotrophic denitrifying bacteria (Acidovorax, Arenimonas, etc.) in the SFe-sludge system after 38 days of operation was found to be 10.6 % higher than that in the ordinary sludge reactor. The aerobic denitrifying bacteria (Dokdonella, Phaeodactylibacter, etc.) was 5.3 % higher than ordinary sludge. The SFe-sludge system improved denitrification by enriching autotrophic/aerobic denitrifying bacteria in low carbon-to-nitrogen ratio wastewater treatment.

CMOS inverter performance degradation and its correlation with BTI, HCI and OFF state MOSFETs aging

In this work, CMOS inverters are subjected to electrical stress emulating a complete operation cycle and the shifts in the performance parameters (i.e., peak current and inversion voltage) evaluated. Moreover, degradation of the two MOSFETs is also measured as variations of their threshold voltage and mobility. The relationships between the observed transistors and circuit parameter shifts are explained in terms of the different device aging mechanisms (i.e., BTI, CHI and OFF-state) that are active depending on the voltages at the circuit terminals. Moreover, the combined effects of the aging mechanisms that are sequentially activated, at device and circuit levels, and their voltage dependence, are also discussed. Finally, a power law fitting of the inversion voltage degradation of the inverter is used to evaluate its variation at operating conditions.

Key performance indicators regarding user comfort for building energy consumption management

This paper proposes an optimization approach to minimize the power consumption of an office building considering user comfort and key performance indicators. The present approach implements the power reduction by reducing power consumption of lights and air conditioners as reducible loads, and implements load shifting by considering dishwasher as shift able load. Two key performance indicators and several comfort parameters are defined to limit the power reduction of lights and air conditioners to consider the user comfort. In the context of load shifting, the complete operation cycle of dishwasher should be shifted without interruption based on the priority weight of the periods and available power. In the present optimization approach, sufficient number of periods have been considered for running the optimization, considering operational constraints and multiple levels for key performance indicators to evaluate their effectiveness. The case study of the work contains six different scenarios to validate different characteristics of the approach. Real consumption data of 20 lights, 10 air conditioners and 1 dishwasher in 20 working days have been applied to implement six different scenarios to propose a real comparable view of present approach.

Quantum Otto engine working with interacting spin systems: Finite power performance in stochastic thermodynamics.

A quantum Otto engine using two-interacting spins as its working medium is analyzed within framework of stochastic thermodynamics. The time-dependent power fluctuations and average power are explicitly derived for a complete cycle of engine operation. We find that the efficiency and power fluctuations are affected significantly by interparticle interactions, but both of them become interaction-independent under maximal power via optimizing the external control parameter. The behavior of the efficiency at maximum power is further explained by analyzing the optimal protocol of the engine.

Failure analysis of a heat-resistant stainless steel ring in a gas turbine burner

Hot gas path components in gas turbines are damaged by several mechanisms due to aggressive environments. In this research, the cracking of an insert ring, which is composed of Nb-stabilized heat-resistant stainless steel, after 8000 operation hours, is investigated. The microstructure of the ring is examined by optical and scanning electron microscopes equipped with energy-dispersive X-ray spectroscopy. The generated stress and strain within the ring during a complete operation cycle (startup to shutdown) of gas turbine are simulated by finite element simulation software. The microstructural investigations indicate the formation of some precipitates that mainly contain nitrogen atoms. The development of tensile loads within the ring during shutdown and brittle N-contained precipitates leads to cracking. The indicators of both types of hot corrosion are also observed.

A comprehensive parametric study on integrated thermal and mechanical performances of molten-salt-based thermocline tank

The numerical model of a molten-salt-based thermocline tank with multi-layer wall structure is established. A comprehensive parametric study on integrated thermal and mechanical performances of the tank is conducted by using the CFD approach. The effects of eight factors are investigated. For all factors, complete operation cycle simulations of the tank as well as mechanical calculations are launched. The effect laws are revealed and briefly summarized. The results indicate that the inlet molten salt velocity, cold molten salt temperature, porosity of porous bed, diameter, thermal conductivity and specific heat of solid filler particle all have relatively obvious impacts on the discharging performance of the tank. The thermocline thickness during the discharging process can be decreased by increasing the inlet molten salt velocity, cold molten salt temperature or specific heat of filler particle, or by reducing the porosity of porous bed, diameter or thermal conductivity of solid filler particle. The maximum mechanical stress of the steel wall can be decreased by increasing the inlet molten salt velocity, cold molten salt temperature or firebrick thickness, or by decreasing the steel wall thickness, porosity of porous bed, diameter, thermal conductivity or specific heat of solid filler particle.

Modeling and thermodynamic cycle analysis of condensation-induced depressurization

A condensation-induced depressurization and steam purging technology has been recently developed to drive a continuous gas flow at a sub-atmospheric pressure. The technology is based on a continuous regeneration of depressurization by a system of two or multiple alternatively-operated chambers with steam condensation and refilling. Comparing with traditional methods, this new vacuum generation technology has a great potential of high energy conversion and utilization for an open-flow system. A complete operation cycle of each chamber undergoes three stages in sequence: vacuum generation by condensing pre-refilled steam, vacuuming gas from application system, and purging gas out of chamber while refilling steam. This paper presents a mechanistic model of process characteristics and parametric analysis for the thermodynamic cyclic operations. Each process stage has been separately modelled, and the complete cycle characteristics are then integrated by connecting these stages in series. The mechanistic model provides a parametric analysis capability for the optimized operation of the developed technology to vacuum driving continuous gas flows at sub-atmospheric pressures. The model result is compared with experiment data with good match. The parametric study of the steam purging process indicates that increasing the steam flowrate and pre-heating of chamber can effectively reduce the purging time required by 20–40%.

Integrated green scheduling optimization of flexible job shop and crane transportation considering comprehensive energy consumption

Since the energy waste of manufacturing industries exacerbates pollution emissions and directly affects the environment, the energy efficiency optimization of the production process is an effective way to promote cleaner production. The transportation process of a workpiece is non-negligible during the entire workshop production process. Particularly in traditional heavy-duty industrial manufacturing enterprises, the energy consumption of the transportation process accounts for a significant proportion of the total workshop energy consumption. To reduce the comprehensive energy consumption of the machining process and transportation process in an actual manufacturing environment, this paper addresses a novel integrated green scheduling problem of flexible job shop and crane transportation (IGSP-FJS&CT). First, a mixed integer programming (MIP) model is formulated to minimize the total cost of the comprehensive energy consumption and makespan in the IGSP-FJS&CT. In the MIP model, a comprehensive energy consumption model is built to optimize the comprehensive energy efficiency of the crane's complete operating cycle and machining process. Then, an integrated GA-GSO-GTHS algorithm is presented to solve the proposed MIP model. In GA-GSO-GTHS, a genetic algorithm (GA) is employed to perform the global search and a glowworm swarm optimization (GSO) algorithm is applied to perform the local search. The green transport heuristic strategy (GTHS) is proposed to guide the search direction of the GA-GSO algorithm. Finally, the performance and effectiveness of the proposed method are demonstrated in a case study. In China's traditional heavy industry manufacturing enterprises, the workshop production is mainly scheduled by manual dispatcher. Consequently, the proposed method has a wide application background in improving energy waste of workshop production, which provides a guiding significance on promoting cleaner production of traditional heavy industry manufacturing.

Quantifying soil movement by forest vehicles with corpuscular metal tracers

Bulk soil movement caused by human impact is hard to quantify. In forestry the bulk soil displacement by passage with heavy machinery is virtually unknown. We present a new method to measure such soil movement with hollow corpuscular metal tracers (16 mm pieces of thin-walled metal pipes made of iron, aluminum, copper and lead) and a metal detector. The tracers are installed minimally invasive into the soil before and located with a metal detector after logging operations. To correctly interpret these measurements it is crucial to know about the accuracy and precision of the method, especially under varying soil moisture content or if different tracer materials are present. To address these questions a series of experiments under controlled conditions on soils with differing iron oxide concentrations were conducted. Best performance on all soils showed Al-tracers, whereas Fe-tracers are limited by increasing Fe-oxide concentrations. Cu and Pb failed. Material specific detection is limited to soils poor in Fe-oxides. Tracers were accurately detectable up to 15–20 cm depth depending on soil moisture. As the signals of the metal detector leave room for interpretation handling needs individual training to obtain unbiased results. In a case study from timber harvesting operations on sloping terrain in Central Europe the tracers where successively moved by each passage of the harvesting machines. After a complete operating cycle the histogram of displacement matched a heavy tailed distribution with a median of around 10 cm and a maximum of several meters. Displacement was reduced by the use of a traction supporting winch. However uncertainty remains whether tracer displacement exactly reflects bulk soil movement.

Assessment of Environmental Impacts of Limestone Quarrying Operations in Thailand

Abstract Environmental impacts of the mineral extraction have been a public concern. Presently, there is widespread global interest in the area of mining and its sustainability that focused on the need to shift mining industry to a more sustainable framework. The aim of this study was to systematically assess all possible environmental and climate change related impacts of the limestone quarrying operation in Thailand. By considering the life cycle assessment method, the production processes were divided into three phases: raw material extraction, transportation, and comminution. Both IMPACT 2002+ and the Greenhouse Gas Protocol methods were used. Results of IMPACT 2002+ analysis showed that per 1 ton crushed limestone rock production, the total depletion of resource and GHGs emissions were 79.6 MJ and 2.76 kg CO2 eq., respectively. Regarding to the four damage categories, ‘resources’ and ‘climate change’ categories were the two greatest environmental impacts of the limestone rock production. Diesel fuel and electricity consumption in the mining processes were the main causes of those impacts. For climate change, the unit of CO2 eq. was expressed to quantify the total GHGs emissions. Estimated result was about 3.13 kg CO2 eq. per ton limestone rock product. The results obtained by the Greenhouse Gas Protocol were also similar to IMPACT 2002+ method. Electrical energy consumption was considered as the main driver of GHGs, accounting for approximately 46.8 % of total fossil fuel CO2 emissions. A final point should be noted that data uncertainties in environmental assessment over the complete life cycle of limestone quarrying operation have to be carefully considered.

Uses of on–off controller for regulation of higher-order system in comparator mode

Design of a control circuit consists of switching algorithm specification which is then implemented in the control system. Problem of specification of switching algorithm comes from the analysis of regulated system’s behaviour in input switching mode. This paper presents the analysis of complete operation cycle for a regulated static system of second order.

Nitrogen and cod removal from tannery wastewater using biological and physicochemical treatments

An integrated wastewater treatment was evaluated for nitrogen and COD removal from a tannery effluent. The system was conformed by the combination of a biological treatment using a sequencing batch reactor (SBR) followed by a physicochemical treatment based in a coagulation-flocculation process. The contaminants in the tannery wastewater had average concentrations of 1546 mg COD·L−1, 200 mg TKN·L−1 and 121 mg N-NH4+ ·L−1. The duration of a complete SBR operation cycle was 12 h. Dissolved oxygen (DO), pH and oxidation–reduction potential (ORP) were used to monitor biological nutrient removal process in the reactor. In addition, densities of nitrifying and denitrifying microorganisms in the mixed liquor were evaluated during the biological treatment. During physicochemical treatment, the concentrations of FeCl3 .6H2 O and sour brine (agroindustrial waste used as adjuvant) were 2.7 and 100 g·L-1, respectively (doses were 60 and 5 mL·L-1, respectively). Results show the integrated treatment system was effective to produce an effluent suitable for discharge into water bodies, according to the Venezuelan environmental regulations. Average effluent concentrations were 303 mg COD L−1, 35.1 mg TN·L−1 and 0.5 mg N-NH4 + ·L-1, giving COD, TN and N-NH4 + removals of 80%, 82% and 99.6%, respectively. Profiles of ORP, DO and pH were efficient ways to monitor the evolution of biological nutrient removal and real-time control can be implemented in order to optimize the SBR operation. Finally, density of nitrifying bacteria was greater than density of denitrifying bacteria during biological treatment.

Water Budgeting of Portable FRP Carp Hatchery for Rohu, Labeo Rohita Spawn Production

Water budgeting experiments were conducted in three portable FRP carp hatchery units installed in three different places of Odisha State, India. Induced breeding programmes were conducted for spawn production for seven times in these FRP hatcheries taking rohu, Labeo rohita as the test species. Water requirement for one complete cycle of FRP carp hatchery operation was calculated to be 105 - 136.3 m3, when spawn production ranged between 0.7 and 1.4 million per operation in field condition. It was estimated that the water requirement per 0.1 million spawn production ranged between 8.86 - 15.01 m3. It was concluded that the water requirement for FRP carp hatchery operation was comparatively more when less quantity of carp spawn produced and was less when more spawn produced.

Comprehensive Study of a Sorption-Based Storage Vessel with Thermal Control for Gaseous Fuel

The authors have presented a calculation model for a gas storage vessel with a microporous adsorbent and a heat pipe with radial fi nning. The model was verifi ed by experimental data derived during the testing of a methane storage vessel in the regime of complete operating cycle. The authors have given the results of parametric investigation which confi rm the important role of the factor of cooling of the adsorbent layer during the charging of the storage vessel.

Dynamic simulation of a triple-pressure combined-cycle plant: Hot start-up and shutdown

The operation of combined-cycle power plants is increasingly determined by frequent start-ups and shutdowns for grid balancing. This study investigates the capability of a comprehensive process simulation model to predict the transient response of a triple-pressure heat recovery steam generator (HRSG) with reheater to the start-up and shutdown procedures of a heavy-duty gas turbine. The model is based on geometry data, system descriptions and heat transfer calculations established in the original HRSG design. The numerical solution approach and the practical development of a suitable model structure, including the required control circuits, are explained. Detailed simulation results are presented, using initial conditions that correspond to a previous overnight shutdown. Calculations are performed for a complete operating cycle of the plant, where the following main phases are distinguished: start-up procedure, load-following operation, design operation and shutdown procedure. The numerical model is validated with measurement data of the commercial power plant for each pressure stage, yielding good agreement. Deviation from the transient behaviour of the real plant is discussed with regard to modelling assumptions and incomplete information on components outside the HRSG system boundaries.

A low-power, time-division-multiplexed vector matrix-multiplier for a vestibular prosthesis.

A custom analog vector matrix multiplier (VMM) for a vestibular prosthesis is reported. The VMM functions to reduce misalignment between implanted angular rate sensors and associated peripheral sense organs and precompensate for spurious electrical stimulation of vestibular neurons. Operating in the CMOS subthreshold region, the VMM performs a 3-by-3 vector matrix multiplication of rate sensor outputs, magnitude <; ±250 mV, and bandwidth <; 1.25 kHz. To reduce susceptibility to device mismatches, time-division-multiplexed multiplication is employed requiring 727 μs for a complete operation cycle. Fabricated with TSMC 0.35 μm CMOS technology, the footprint is 1523 μm × 1548 μm and consumes 5.37 μW of power.

The Definition of the Enterprise’s Efficiency under Condition of Uncertainty Using Gestalts System

The article shows the process of creating a enterprise's gestalt system for decision-making under uncertainty. The gestalt system is a model that relies on the analysis of the internal and external environment of the enterprise. Practical calculations are made on the basis of Tsurupinsk Ltd. The final phase of the system as a gestalt model for decision making under uncertainty is described. The complete cycle of operation of gestalt system is showed. The practical calculations within the system with the output node and integral values have been done. The application of gestalts system of enterprises under uncertainty is justified.

Numerical study of intrachamber processes dynamics at nozzleless solid propellant rocket engine actuation

The results of the comprehensive numerical analysis for dynamics of intrachamber processes that appear at nozzleless solid propellant rocket engine (SPRE) actuation are presented. A complete cycle of rocket engine operation is analyzed. We solve a conjugate problem involving the igniter actuation; heating, ignition and following combustion of a solid propellant charge; a combustion product flow in the combustion chamber; depressurization of the combustion chamber, and the subsequent motion of the rocket engine blank; variation of the combustion surface geometry at the expense of the gradual and nonuniform burnout of solid propellant web.

Effects of Pre-fermentation and Influent Temperature on the Removal Efficiency of COD, NH4+-N and PO43–-P in Slaughterhouse Wastewater by Using SBR

A sequencing batch reactor (SBR) was used to remove COD, NH4+-N and PO43--P in slaughterhouse wastewater at different temperatures. A complete operation cycle was 7h, which consisted of fill, aeration(5h), settling(1h), stationary(1h) and drawing. Conventional treatment technologies were unsuccessful in treating slaughterhouse wastewater because it contained substantial amounts of fat, oil and grease (FOG). The SBR process showed great nutrient removal performances after 7 days prefermentation. The removals of COD, NH4+-N and PO43--P were 99%, 85% and 99%, respectively. The increase in effluent volatile fatty acid (VFA) and phosphate concentrations after prefermentation may explain the high levels of biological carbon, nitrogen and phosphorus removal observed. The results also showed that 30 C was found to be the most suitable temperature as the removal efficiency of COD, NH4+-N and PO43--P was 96%, 92% and 91%, respectively.