scholarly journals Особенности импульсного нагрева излучением субтерагерцевого гиротрона при получении нанопорошков оксидов металлов

2020 ◽  
Vol 46 (15) ◽  
pp. 33
Author(s):  
А.В. Водопьянов ◽  
Д.А. Мансфельд ◽  
А.И. Цветков ◽  
А.А. Орловский
Keyword(s):  
Duty Cycle ◽  
Average Power ◽  
Linear Increase ◽  
Continuous Heating ◽  
Optimal Conditions ◽  
Radiation Beam ◽  
Pulsed Heating ◽  
Short Time ◽  
Heating Mode ◽  
Subterahertz Radiation

The paper describes the features of the metal oxide nanopowder obtaining by an evaporation-condensation method with pulsed heating of the material by focused subterahertz radiation. It has been experimentally shown that optimal conditions for the rapid evaporation of a substance are achieved at the highest possible pulse power and the lowest possible duty cycle at a fixed average power. Under these conditions, it is possible to realize the heating and evaporation of a substance in a focused radiation beam in a relatively short time, while the adjacent layers of the substance maintain a relatively low thermal conductivity. A linear increase in the evaporation rate with a decrease in the duty cycle of heating pulses was demonstrated, the increase reached 5 times relative to the continuous heating mode.

High-average-power, high-duty-cycle (λ∼6 μm) quantum cascade lasers

2002 ◽  
Vol 81 (23) ◽  
pp. 4321-4323 ◽  
Author(s):  
S. Slivken ◽  
A. Evans ◽  
J. David ◽  
M. Razeghi
Keyword(s):  
Duty Cycle ◽  
Quantum Cascade Lasers ◽  
Average Power ◽  
High Average Power ◽  
Quantum Cascade ◽  
High Duty Cycle ◽  
Cascade Lasers

Crystallization of Amorphous Ribbon in NiTi-Cu Shape Memory Alloy

1997 ◽  
Vol 481 ◽  
Author(s):  
F. Yang ◽  
J. L. Ma ◽  
Z. J. Pu ◽  
K. H. Wu
Keyword(s):  
Shape Memory ◽  
Crystallization Kinetics ◽  
System Analysis ◽  
Crystallization Process ◽  
Amorphous Material ◽  
Amorphous Ribbon ◽  
Continuous Heating ◽  
Isothermal Model ◽  
Heating Mode ◽  
Kinetics Of

ABSTRACTThe objective of this work is to study the crystallization process of the amorphous ribbon of NiTi-Cu based shape memory alloys. An amorphous material with a composition of Ti50Ni25Cu25 was used to conduct this study. First, a study was conducted to understand the crystallization kinetics of this amorphous material at the isothermal model and continuous heating mode, respectively. The characteristic parameters associated with the crystallization process, such as the start and finish time for isothermal crystallization, the peak temperature for continuous heating crystallization, and activation energy, are obtained. Based on the study of experimental data of crystallization kinetics, a series of isothermal annealing experiments was conducted to study the crystallization process and microstructure of fully crystallized materials. The TEM micrograph shows the crystal phase growths in the amorphous matrix as a perfect geometric sphere. A system analysis was conducted to explain the crystallization micro-mechanism.

As(III) removal by Fe(III)-amidoximated PAN in the presence of H2O2 through simultaneous oxidation and adsorption

2019 ◽  
Vol 20 (2) ◽  
pp. 565-573
Author(s):  
Luyao Gao ◽  
Mengna Hao ◽  
Fanling Bu ◽  
Chunnuan Ji ◽  
Rongjun Qu ◽  
...  
Keyword(s):  
Adsorption Process ◽  
Arsenic Removal ◽  
Ph Value ◽  
Dynamic Adsorption ◽  
Optimal Conditions ◽  
Efficient Removal ◽  
Simultaneous Oxidation ◽  
Simulated Groundwater ◽  
Ph Range ◽  
Short Time

Abstract This study explored the efficient removal of As(III) by Fe(III)-amidoximated PAN (Fe(III) AO PAN) in the presence of H2O2 through simultaneous oxidation and adsorption. It presented that As(III) could be oxidized to As(V) efficiently in the pH range 3–9 within a short time. At the same time, the oxidized As(V) was adsorbed by Fe(III)-AO PAN. The effect of pH value, H2O2 concentration, Fe(III)-AO PAN amount, and coexisting anions on the As(III) oxidation and removal were investigated in detail. Dynamic adsorption on fixed column was also studied. Arsenic removal efficiency including As(III) and As(V) could be achieved (95.2%) by the simultaneous oxidation and adsorption process at the following optimal conditions: pH = 6.5, dosage of Fe(III)-AO PAN = 2.5 g/L, H2O2 = 100 mg/L, initial concentration of As(III) = 5 mg/L. Dynamic adsorption on fixed column demonstrated that As(III) in simulated groundwater could be efficiently removed from 500μg/L to <10 μg/L within 130 bed volumes (BV).

Numerical Simulation Analysis on Residential Building Indoor Thermal Environment of Intermittent Heating in Lhasa Based on DeST

2012 ◽  
Vol 462 ◽  
pp. 215-220 ◽  
Author(s):  
Ying Ying Wang ◽  
Yan Feng Liu ◽  
Deng Jia Wang
Keyword(s):  
Simulation Analysis ◽  
Thermal Environment ◽  
Residential Buildings ◽  
Residential Building ◽  
Simulation Software ◽  
Continuous Heating ◽  
Indoor Thermal Environment ◽  
Intermittent Heating ◽  
Save Energy ◽  
Heating Mode

The aim of this paper is to analyze whether the intermittent heating mode is feasible for residential buildings in Lhasa, the thermal parameters of each palisade structure and the influence law of intermittent heating mode on the indoor thermal environment. In this paper, the DeST energy consumption simulation software that is compiled by Tsinghua University was used to simulate and analyze a residential building in Lhasa city. The results show that: It is completely feasible to carry out intermittent heating in Lhasa area. Considering the indoor temperature reduction should not be too large during intermittent heating break, it is recommended to adopt external insulation. Compared with continuous heating mode, heating open 8 hours and 12 hours a day can save energy 24% and 39% respectively. The results can provide evidences for intermittent heating operating control and energy- saving.

scholarly journals Smart Cutting Tools Used in the Processing of Aluminum Alloys

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 28
Author(s):  
Dan Dobrotă ◽  
Sever-Gabriel Racz ◽  
Mihaela Oleksik ◽  
Ionela Rotaru ◽  
Mădălin Tomescu ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Fourier Transformation ◽  
Vibration Analysis ◽  
Cutting Tools ◽  
Optimal Conditions ◽  
The Finite Element Method ◽  
Intelligent Tools ◽  
Longitudinal Turning ◽  
Short Time ◽  
Short Time Fourier Transformation

The processing of aluminum alloys in optimal conditions is a problem that has not yet been fully resolved. The research carried out so far has proposed various intelligent tools, but which cannot be used in the presence of cooling-lubricating fluids. The objective of the research carried out in the paper was to design intelligent tools that would allow a control of the vibrations of the tool tip and to determine a better roughness of the processed surfaces. The designed intelligent tools can be used successfully in the processing of aluminum alloys, not being sensitive to coolants-lubricants. In the research, the processing by longitudinal turning of a semi-finished product with a diameter Ø = 55 mm of aluminum alloy A2024-T3510 was considered. Two constructive variants of smart tools were designed, realized, and used, and the obtained results were compared with those registered for the tools in the classic constructive variant. The analysis of vibrations that occur during the cutting process was performed using the following methods: Fast Fourier Transform (FFT); Short-Time Fourier-Transformation (STFT); the analysis of signal of vibrations. A vibration analysis was also performed by modeling using the Finite Element Method (FEM). In the last part of the research, an analysis of the roughness of the processed surfaces, was carried out and a series of diagrams were drawn regarding curved profiles; filtered profiles; Abbott–Firestone curve. Research has shown that the use of smart tools in the proposed construction variants is a solution that can be used in very good conditions for processing aluminum alloys, in the presence of cooling-lubrication fluids.

scholarly journals Numerical simulation and experimental verification of laser multi-section welding

2020 ◽  
Author(s):  
Jia Liu ◽  
Tao Jiang ◽  
Yan Shi ◽  
Hongyin Zhu ◽  
Yuchi Dai
Keyword(s):  
Numerical Simulation ◽  
Duty Cycle ◽  
Average Power ◽  
Welding Process ◽  
Element Model ◽  
Simulation Software ◽  
Experimental Results ◽  
Welding Method ◽  
Laser Lap Welding ◽  
Lap Welding

Abstract Aiming at the problems of large welding deformation and spatter in resistance spot welding of traditional lube oil cooler plate, a new welding method: laser multi-section welding is proposed. The major processes here involved were a finite element model of pulsed laser lap welding established using SYSWELD simulation software, and the laser welding process of different welding methods. Study the influence of different welding methods on welding quality, Optimize the parameters of average power and duty cycle according to the comparative analysis of experimental results and numerical simulation Experimental results indicate: When the new 6-sections welding method is adopted, the resulting welded joint has the most uniform heat input, the largest welding fusion area, the tensile properties of the welded joints were significantly improved, however, there are still pores. By changing the duty cycle, air holes can be effectively eliminated to further improve the quality of the joint.

Investigation on the Energy Efficiency of Innovative Hybrid Impact Hydroforming

2014 ◽  
Vol 989-994 ◽  
pp. 1282-1285 ◽  
Author(s):  
Shao Hua Wang ◽  
Li Hui Lang ◽  
Li Jing Lin
Keyword(s):  
Energy Efficiency ◽  
Impact Energy ◽  
Technology Use ◽  
High Energy ◽  
Linear Increase ◽  
Simulation Software ◽  
Gas Pressure ◽  
Energy Output ◽  
Short Time ◽  
The Impact

The innovative hybrid impact hydroforming (IHF) technology use high energy forming complex parts in very short time which can improving forming quality of hardforming materials like Aluminum alloy widely used in automotive and aircraft industries. The impact hydroforming technology means the most features are formed by hydroforming and the small features are rapidly reshaped by high intensity impact energy in a very short time after the traditional hydroforming. Thus, the impact energy is the most important parameter of Innovative Hybrid Impact Hydroforming. Using numerical simulation software MSC.PATRAN/DYTRAN, the whole system of hybrid impact hydroforming apparatus was analyzed. The initial gas pressure and the mass of hammer directly affect the energy efficiency. The results show greater initial gas pressure will linear increase the energy output. Moreover, the bigger mass of hammer will reduce the velocity of hammer, but it still increase the energy output. Therefore, the research is very useful for improving energy efficiency of IHFand widing its application.

Small Floating Target Detection Algorithm Based on Time-Frequency Similarity

2014 ◽  
Vol 1030-1032 ◽  
pp. 1805-1809
Author(s):  
Jin Jiang ◽  
Ming Li ◽  
Yan Shen ◽  
Chong Yi Li
Keyword(s):  
Target Detection ◽  
Average Power ◽  
Detection Algorithm ◽  
Observation Time ◽  
Similarity Analysis ◽  
Mean Square ◽  
Time Frequency ◽  
Radar Echo ◽  
Time Average ◽  
Short Time

The features of radar echo of small floating target within sea clutter exists not only in target bins, but also exist in extend range bins. These lead to certain characteristic are similar between targets and extend bins. Short-time average power and mean-square Doppler bandwidth are extracted as two of these features and their similarities are been proved existing between target bin and extend bins by IPIX data. Although clutter bins may also have this similarity, it could be distinguished when observation time is enhanced. According to this characteristic, a detection algorithm is proposed based on time-frequency similarity analysis, the method works well when the average signal clutter ratio is about 5dB and the observation time is 300ms.

Description of short time phase transformations during the heating of steels based on high-rate experimental data

2004 ◽  
Vol 120 ◽  
pp. 591-598
Author(s):  
T. Mioković ◽  
J. Schwarzer ◽  
V. Schulze ◽  
O. Vöhringer ◽  
D. Löhe
Keyword(s):  
Phase Transformations ◽  
High Rate ◽  
Temperature Fields ◽  
Continuous Heating ◽  
Heating Rates ◽  
Temperature Changes ◽  
Steel Aisi ◽  
Temperature Transformation ◽  
Transformation Diagrams ◽  
Short Time

During surface hardening of steels like laser hardening, rapid thermal changes are imposed to the material. The modelling of these hardening processes allows the determination of time-dependent temperature fields and phase transformations within the affected zones. While there are many investigations on the transformation behaviour during cooling, there is a lack of data concerning the transformation during heating at very high heating rates. Therefore, experiments simulating the fast temperature changes are necessary to implement the effects of short time phase transformation during hardening into simulation. In this paper the effect of heating rates up to 10000 K/s on the austenitizing behaviour of the steel AISI 4140 (German grade 42CrMo4) are presented and described using an Avrami-function. The results obtained are summarized in time-temperature-transformation diagrams for continuous heating and isothermal time-temperature-transformation diagrams which may be used as input data for the simulation.

scholarly journals Research on the Transient Characteristics of Microgrid with Pulsed Load

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Jianke Li ◽  
Jinquan Wang ◽  
Ye Xu ◽  
Haitao Zhang ◽  
Chunming Wang ◽  
...  
Keyword(s):  
Duty Cycle ◽  
Peak Power ◽  
Average Power ◽  
Synchronous Generator ◽  
System Dynamic ◽  
Cycle Period ◽  
Resistive Load ◽  
Insulated Gate Bipolar Transistor ◽  
Deviation Rate ◽  
The Impact

Unlike traditional load, pulsed load typically features small average power and large peak power. In this paper, the mathematic models of microgrid consisting of synchronous generator and pulsed load are established. Average Magnitude Difference Compensate Function (AMDCF) is proposed to calculate the frequency of synchronous generator, and, based on AMDCF, relative deviation rate (RDR) which characterizes the impact of pulsed load on the AC side of grid is firstly defined and this paper describes calculation process in detail. Insulated Gate Bipolar Transistor (IGBT) is used as DC switch to control the on/off state of resistive load for simulating pulsed load, the period and duty-cycle of the pulsed load are simulated by setting the gate signal of IGBT, and the peak power of the pulsed load is simulated by setting the resistance. The system dynamic characteristics under pulsed load are analyzed in detail, and the influence of duty-cycle, period, peak power, and filter capacitance of the pulsed load on system dynamic indicators is studied and validated experimentally.

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