Underground mining production process is vulnerable and highly dynamic in nature. Among the various causes of accidents in underground mine, major one is presence of flammable and noxious gases. Though many existing safety gadgets are there but they could not work reliably because of the typical nature of mines structure and production variability. Wireless data and communication network is also not successful because wireless communication in underground mine is significantly more challenging than through air. This work introduces the application of mobile wireless sensor network in order to monitor a variety of parameters in underground mines which have life threatening effects towards them. Each node of the network placed over the safety gear (helmet wore statutorily by every miner) comprises of various sensors depending on the requirement with microcontroller unit and other low power accessories. The proposed work has a unique feature that it will make the personnel aware about the situation of the gases present and surrounding by automatically generating different alarms and different light indicators. Other function of this device will be to transmit the data sensed by the sensors in the device to the control room wirelessly so that the responsible person would be aware of the situation. This work is focused on the design of such a prototype model for the underground mines with the aforementioned specification. 相似文献
The insufficient strategies to improve electronic transport, the poor intrinsic chemical activities, and limited active site densities are all factors inhibiting MXenes from their electrocatalytic applications in terms of hydrogen production. Herein, these limitations are overcome by tunable interfacial chemical doping with a nonmetallic electron donor, i.e., phosphorization through simple heat‐treatment with triphenyl phosphine (TPP) as a phosphorous source in 2D vanadium carbide MXene. Through this process, substitution, and/or doping of phosphorous occurs at the basal plane with controllable chemical compositions (3.83–4.84 at%). Density functional theory (DFT) calculations demonstrate that the P? C bonding shows the lowest surface formation energy (ΔGSurf) of 0.027 eV Å?2 and Gibbs free energy (ΔGH) of –0.02 eV, whereas others such as P‐oxide and P? V (phosphide) show highly positive ΔGH. The P3–V2CTx treated at 500 °C shows the highest concentration of P? C bonds, and exhibits the lowest onset overpotential of –28 mV, Tafel slope of 74 mV dec?1, and the smallest overpotential of ‐163 mV at 10 mA cm?2 in 0.5 m H2SO4. The first strategy for electrocatalytically accelerating hydrogen evolution activity of V2CTx MXene by simple interfacial doping will open the possibility of manipulating the catalytic performance of various MXenes. 相似文献
The scintillator detectors are recalibrated against the datasheet given by the manufacturer. Optimal and mutual dependent values of (a) high voltage at PMT (Photomultiplier Tube), (b) amplifier gain, (c) average time to count the radiation particles (set by operator), and (d) number of instances/sample number are estimated. Total 5: two versions of Central Limit Theorem (CLT), (3) industry preferred Pulse Width Saturation, (4) calibration based on MPPC coupled Gamma-ray detector, and (5) gross method are used. It is shown that the CLT method is the most optimal method to calibrate the detector and its respective electronics couple. An inverse modeling-based Computerized Tomography method is used for verification. It is shown that statistically averaging results are more accurate and precise data than mode and median if the data is not skewed and a random number of samples are used during the calibration process. It is also shown that the average time to count the radiation particle is the most important parameter affecting the optimal calibration setting for precision and accurate measurements of gamma radiation.
In this work, quaternary chalcogenide Cu2ZnSnSe4 (CZTSe) was synthesized using a mechanochemical ball milling process and its thermoelectric properties were studied by electrical resistivity, Seebeck coefficient, and thermal conductivity measurements. The synthesis process comprises three steps viz., wet ball milling of the elemental precursors, vacuum annealing, and densification by hot pressing. The purpose of this is to evaluate the feasibility of introducing wet milling in place of vacuum melting in solid state synthesis for the reaction of starting elements. We report the structural characterization and thermoelectric studies conducted on samples that were milled at 300 rpm and 500 rpm. X-ray diffraction (XRD) analysis showed the existence of multiple phases in the as-milled samples, indicating the requirement for heat treatment. Therefore, the ball milled powders were cold pressed and vacuum annealed to eliminate the secondary phases. Annealed samples were hot pressed and made into dense pellets for further investigations. In addition to XRD, energy dispersive spectroscopy (EDS) studies were performed on hot pressed samples to study the composition. XRD and EDS studies confirm CZTSe phase formation along with ZnSe secondary phase. Electrical resistivity and Seebeck coefficient measurements were done on the hot pressed samples in the temperature range 340–670 K to understand the thermoelectric behaviour. Thermal conductivity was calculated from the specific heat capacity and thermal diffusivity values. The thermoelectric figure of merit zT values for samples milled at 300 rpm and 500 rpm are ~0.15 and ~0.16, respectively, at 630 K, which is in good agreement with the values reported for solid state synthesized compounds. 相似文献
In the design of a Computer Communication Network (CCN), the reliability between any pair of nodes and the maximum permissible installation cost are of great importance. These characteristics are largely dependant upon the topological layout of the links, their costs and reliabilities. Having the knowledge of the topological layout of the various computer centres (nodes) and maximum permissible cost of installing the various links at their pre-assigned positions; in this paper an algorithm for obtaining an optimal network topology which gives the maximum s?t reliability is presented. The developed method is general and is computerized. The proposed method has an additional advantage that the system is not to be redesigned, if at a later stage the permissible cost is enhanced by budgetary provisions. An example illustrates the algorithm. 相似文献
A passive auxiliary circuit is proposed to achieve zero-voltage-switching (ZVS) over the entire conversion range in a full-bridge (FB) pulse-width modulated (PWM) converter (FBZVS converter) with minimum conduction loss penalty. The stored energy in the auxiliary circuit is minimal under the full-load condition. It increases progressively as the load current decreases. The proposed auxiliary circuit is passive, simple and can be viewed as an add-on to the conventional FBZVS converter. The principle of operation is described and the performance is demonstrated on a 100 kHz, 500 W prototype. 相似文献
Unlike traditional networking devices, control and management plane are decoupled from data plane in software‐defined networks (SDN). The logically centralized control and management plane facilitate dynamic orchestration of network resources, services, and policies by writing software programs. This provides much needed flexibility and programmability where networking rules and policies can be modified dynamically depending upon the application context. As the operation of network services entirely depends on a program, a small fault may induce several issues which can adversely affect the expected behavior of the network. Formal modeling and verification help in catching inconsistencies and existence of errors prior to the deployment of the programs that control the behavior of a network. In this paper, we provide a comprehensive survey of tools and techniques available in the literature for formal modeling and verification of SDN. These tools and techniques are classified based on their types, the components of SDN where they can be applied, and the design and development phase when they are utilized. In particular, their respective benefits and limitations are discussed in terms of ease of use, interfaces, and the ability to capture and verify intended network properties. 相似文献