Explosive Rate Research Articles

Impacts of turbulence on explosion characteristics of methane-air mixtures with different fuel concentration

To study the effects of turbulence on the typical explosion characteristics (the maximum explosion pressure pmax, the explosion duration time τe, the maximum rate of pressure rise (dp/dt)max and the deflagration index KG) of methane-air mixtures, experiments are conducted in a standard 20-L explosion spherical vessel, the concentration of methane varies from 0.06 to 0.15, the mixtures are ignited by a spark in the end-wall of the vessel. The purpose of this study aims to further probe the relationship between the positive turbulence-enhancement effect and the negative inert gas inhibition effect in methane-air mixture with the conditions that covering the entire flammability limit. The turbulence is generated when a N2 jet is promptly injected into the chamber from a high-pressure storage tank via a solenoid valve, and the initial pressure of the storage tank pJ0 is set as 500 kPa. The explosion behavior of methane-air mixture under the effect of turbulence is firstly compared with that in quiescent conditions. For quiescent explosions, adding a small amount of N2 into the methane-air mixture has no notable impact on the explosion behavior, while a relatively large amount of N2 significantly slows down the explosion rate, but it has little influence on pmax. Furthermore, the influence of turbulence associated with different concentration of methane on the explosion behavior is systematically analyzed. The results of quiescent explosions indicate that, the values of explosion parameters increase with the increasing of p0, by adding N2 dilution, it has a notable effect on reducing (dp/dt)max and this effect is weak on pmax, which is due to the competing mechanism between the positive effect from increased initial pressure and the negative effect of inert gas being achieved to an equilibrium state. By introducing turbulence, results clearly show that the turbulence has a prominent enhancement effect on the explosion, especially as tJ0 within a short time; longer tJ0 does not further contribute in promoting the explosion hazard because of the suppression effect of N2 dilution balances a part of turbulent kinetic energy. The impact of jet turbulence on pmax at the condition near flammability limits is more prominent than that near stoichiometric condition, this behavior is attributed to the mixture being relatively well-reacted when near stoichiometric condition, and thus the positive effect of turbulence on reducing heat loss is weak due to the short reaction time in this case, resulting in a minor change in pmax. The experimental results illustrate that the turbulence-enhancement on explosion is greatly dependent on tJ0 and td, at a critical state when heat loss and turbulence intensity achieve to a best condition during the explosion process, and this state is related to the optimal value of tJ0 and td.

Contribution of starburst nuclei to the diffuse gamma-ray and neutrino flux

ABSTRACT In nuclei of starburst galaxies (SBGs), the combination of an enhanced rate of supernova explosions and a high gas density suggests that cosmic rays (CRs) can be efficiently produced, and that most of them lose their energy before escaping these regions, resulting in a large flux of secondary products, including neutrinos. Although the flux inferred from an individual starburst region is expected to be well below the sensitivity of current neutrino telescopes, such sources may provide a substantial contribution to the diffuse neutrino flux measured by IceCube. Here, we compute the gamma-ray and neutrino flux due to SBGs based on a physical model of CR transport in a starburst nucleus, and accounting for the redshift evolution of the number density of starburst sources as inferred from recent measurements of the star formation rate. The model accounts for gamma-ray absorption both inside the sources and in the intergalactic medium. The latter process is responsible for electromagnetic cascades, which also contribute to the diffuse gamma-ray background at lower energies. The conditions for acceleration of CR protons up to energies exceeding $\sim 10 \, \rm PeV$ in starburst regions, necessary for the production of PeV neutrinos, are investigated in a critical way. We show that starburst nuclei can account for the diffuse neutrino flux above $\sim 200 \, \rm TeV$, thereby producing $\lesssim 40 {\rm { per\, cent}}$ of the extragalactic diffuse gamma-ray background. Below $\sim 200 \, \rm TeV$, the flux from starburst appears to be somewhat lower than the observed one, where both the Galactic contribution and the flux of atmospheric neutrinos may account for the difference.

Carbon Sphere Template Derived Hollow Nanostructure for Photocatalysis and Gas Sensing.

As a green and preferred technology for energy crisis and environmental issues, continuous research on photocatalysis and gas sensing has come forth at an explosive rate. Thus far, promising synthetic methods have enabled various designs and preparations of semiconductor-based nanostructure which have shown superior activity. This review summarized various synthetic routines toward carbon sphere template derived hollow nanostructures and their successful attempts in synthesize doping, solid solution, heterostructure, and surface modified nanostructures for heterogeneous photocatalysis and gas sensing. Moreover, the challenges and future prospects are briefly discussed. It is eagerly anticipated that this review may broaden the view and in-depth understanding of carbon sphere template derived hollow nanostructures while expected to have further progresses in heterogeneous photocatalysis, gas sensing and other related fields which will make great contributions to their application.

Investigation of the explosion severity of multiphase hybrid mixtures

AbstractThis study presents an experimental investigation of the maximum explosion pressure (Pmax) and rate of pressure rise (dP/dt)max of dusts (lycopodium and brown coal), solvents (ethanol, isopropanol), gases (methane and hydrogen) as well as two‐ and three‐phase hybrid mixtures. Experiments were performed in a standard 20 L sphere with a 10‐J electrical igniter as an ignition source and a 60 ms ignition delay time. It was consistently noticed that the explosion severity of a dust and gas/spray hybrid mixture was higher than that of dust, but lower than either gas or solvent. The addition of a flammable gas/spray to a dust‐air mixture increases the maximum explosion pressure to some extent and significantly increases the maximum rate of the dust mixture pressure rise, even though the concentration of the flammable gas/vapor is below its lower explosion limit. For instance, lycopodium with maximum rate of pressure rise value of 272 bar/s increased to 322, 369, 410, and 504 bar/s when methane concentration of 1, 2, 3, and 4 vol% was respectively, added. These values of maximum rate of pressure rise further increased to 430, 460, 573, and 798 bar/s when a nonexplosible concentration of a third‐phase isopropanol (50% lower than the lower explosion limit) was added. From the findings of this research, it could be inferred that one cannot rely on the explosion severity of a single substance to ensure the safety of a process or system when substances with different states of aggregate are present.

A Study to Assess the Effectiveness of Structured Teaching Programme on Knowledge Regarding Substance Abuse and its Impact on Health among Higher Secondary Students among Atulya Healthcare Pune

Context: Healthcare professionals are crucial in the identification and accessibility to treatment for people with substance abuse. The objective of the study was to assess students’ knowledge towards substance use disorders and examine the consequences of these on health. Substance abuse is a social problem, not in India alone, but the entire world. The use of drugs has its own culture and history, which varies from country to country. The problem of substance abuse is growing at an explosive rate and in just little over a decade it has spread its malevolent tentacles to almost every part of the globe surmounting almost all barriers of race, caste, creed, religion, sex educational status, economic strata etc.As the first experience of substance abuse often starts in adolescence, and studies have shown that drug use is mainly related to cigarette and alcohol consumption, an initial exploration of substance abuse prevalence, including cigarette and alcohol, seems to be the first step in preventing and controlling drug consumption.

Microstructure and mechanical properties of Cu/CuCrZr composite plates fabricated by explosive welding

ABSTRACT In this study, three series of Cu/CuCrZr composite plates were successfully achieved by explosive welding (EXW) method. The effect of the explosive rate and buffer plate on the microstructure and mechanical properties of bonding interface were investigated. In the bonding interface, no intermetallic or transition was formed. It was obvious that installing the buffer plate protected the composite plate from excessive ablation. With the increase of rate of explosive, the amplitude and wavelength of wave were increased. Some peninsular molten pockets were observed at the wavy interface adjacent to the wave crest of the three welds, the dimensions of which decreased with the decrease of explosive rate. Microhardness of bonding interface and outer face of plates were increased because of deformation that was originating from impact or reflection of the explosion pressure from the anvil. Microhardness and shear strength values were increased with the increase of explosive rate, while the values of clad plates with the buffer plate installed were more stable.

No. 16 Model House Road

No. 16 Model House Road Sindya Bhanoo (bio) Latha's fingers tug at a loose strand of wicker on the arm of the loveseat. She is sitting next to Muthu on the well-worn, pale green cushions. The developer woman sits across from them, on the matching single sofa. Her toenails are painted a shade of light blue that remind Latha of the soap she uses when she does the laundry. The woman is wearing linen pants and a red cotton shirt, appropriately high-necked and pleasantly loose, with a stylish outward flare at the waist. One of her legs is crossed over the other, and the boldness of this shocks Latha. Not because she thinks women should not cross their legs. She believes that women can do anything. Her own daughter works, and she sees women working on the TV serials she watches. Latha is shocked because, for the first time, she is observing a woman at work—with the style, posture, and demeanor of a professional—right in front of her, in her home. Mornings in Bangalore are typically crisp and cool, but this morning there is a bit of warm sun and it streams through the grilled window, casting a shadow of bars that stretch underneath Latha and Muthu's round, glass-topped coffee table. The woman has her papers spread out over the glass, one page right on top of the plate of butter biscuits that Latha set out: sketches, floor plans, and photographs detailing what things could be like. They could have three bedrooms or four, she says. Right now, they only have two. She directs her words towards Muthu, though it is Latha who actually owns No. 16 Model House Road. Binny left it to her when she died, not to him. "The living area will increase by 50 percent with most options," the woman says, her English clean and crisp. "Remarkable what we can do." The developer's proposal is simple: to demolish Latha's beloved No. 16 and, in its place, erect a thoughtfully constructed, modern, low-rise apartment building. Four stories. Four flats. All costs covered by the company. During the year it would take to construct the new building, the company would cover the cost of Latha and Muthu's housing with a generous lump sum. At the end of it all, the bottom flat would go to Latha and Muthu, and the other three would go to the developer and be sold at a big profit. It was a scheme happening all over Bangalore in various forms, as the city's tech industry grew at an explosive rate. Property values were higher than they had ever been, and housing was almost impossible to find. A few years ago, another developer had offered to buy their plot. Theirs was just a one-and-aquarter–ground plot but that developer had been willing to pay them three crores for it. They declined. [End Page 142] Today, the woman has four layouts for Latha and Muthu to choose from. Latha is partial to the smallest of the floorplans because it offers the most garden space. But she knows Muthu has disregarded it. While Muthu studies the plans, Latha continues to study the woman. Her hair is long, loose, and straight, cut unevenly in the front so that pieces of it touch her cheeks and chin. The unevenness appears to be intentional. She is in her early thirties, Latha thinks, based on her still-firm skin and the presence of a single visible gray hair that runs down from her side part. She is not wearing a thaali around her neck, or a ring, but that means nothing in Bangalore these days. Even Latha's daughter, newly married, only wears her thaali when attending a wedding or some other family function. "From the beginning, I have liked this one," Muthu says. He points to a layout that appears to have an extra room jutting out the back. From the beginning. Muthu had wanted to take the deal the first time the company made a proposal, nearly ten months ago. The woman is the fourth person from the company to come to their...

Effects of particle size distribution on the explosion severity of coal dust

ABSTRACT The effects of particle size distribution (PSD) on coal dust explosion severity were investigated using a 20 L vessel. The severity was evaluated by the maximum explosion pressure (), the maximum rate of pressure rise (), and the time spans (, ) between ignition and and between ignition and during a trial. These parameters of five coal samples with the same particle size span (PSS) and different PSD were measured at 250 . The results show that the explosion rate is greatly affected by PSD. When the finer particles account for 30 wt%, increased significantly, whereas and values decreased. , and are affected significantly by and (the particle size for which 10% and 50% of the particles by projection area) dust components. It is suggested that and should be considered when polydispersity is used to describe the PSD. , , and the Specific Surface Area(SSA) are related to these explosion parameters and provide the better description of the PSD. The smaller the particle size is, the more complete the particles combust and the smaller the calorific values of dust explosion products are.

Assessing an experimental approach for chemical explosive mode and heat release rate using DNS data

Obtaining information about burning characteristics and flame structures by analyzing experimental data is an important issue for understanding combustion processes and pursuing combustion modeling approaches. It has been shown that Raman/Rayleigh measurements of major species and temperature can be used to approximate the local heat release rate and the chemical explosive mode, and that these results are sufficiently accurate for a qualitative assessment of the relative importance of different heat release zones within the same overall flame structure in laminar and mildly turbulent partially premixed flames [1,2]. The present study uses data from direct numerical simulation (DNS) to extend and quantify the understanding of the approximation method with respect to premixed and stratified-premixed flames with significant turbulence–chemistry interaction (high Karlovitz number). The accuracy of the approximation procedure is assessed as previously applied, using just major species and temperature, as well as with the OH radical included as an additional experimentally accessible species. The accuracy of the local chemical explosive mode and the local heat release rate results from the approximation are significantly improved with OH included, yielding quantitative agreement with the DNS results. Further, a global sensitivity analysis is applied to identify the sensitivity of the heat release rate and chemical explosive mode to experimental uncertainties imprinted upon the DNS data prior to the approximation procedure.

A relief supplies purchasing model via option contracts

The demand for relief supplies after sudden disasters strike is growing at an explosive rate. Because of high uncertainty and time urgency, governments usually stockpile a certain amount of relief supplies in advance of potential disasters. Hence governments face inventory risk and stock-out risk in the relief supply management. The stored relief supplies by governments are wasted if no disaster happens. If the quantity of stored relief supplies is not sufficient, stock-out risk will occur. In reality, governments may purchase relief supplies from multiple suppliers, rather than from a supplier. However, few studies have been undertaken with respect to the decision of what quantity of relief supplies should be stockpiled by governments, and how much inventory to pre-position at each supplier. To solve the problem, we introduce option contracts into relief supply management by considering this system as a relief supply chain with one government and multiple suppliers. A relief supplies purchasing (RSP) model via option contracts is established. The government’s optimal order quantity of relief supplies and each supplier’s pre-positioning quantity of relief supplies are derived. We uncover the condition that the relief supply chain coordination is achieved. Under channel coordination, the RSP model can improve the total quantity of relief supplies stockpiled for sudden disasters, and reduce the government’s inventory risk when compared to the government single pre-positioning model. Meanwhile, we give the condition that the government and all suppliers achieve a multi-win situation. Finally, we broaden our model and attain a common interval in which both supplier 1 and supplier 2 are willing to engage. The research findings provide some managerial insights for government’s purchasing strategies.

Method for theoretically predicting time history of afterburning reaction rate of internal explosion and determining energy release constant

Method for theoretically predicting time history of afterburning reaction rate of internal explosion and determining energy release constant

Quality by Design (QbD) Concept: A Potential Solution to Chinese Current Biomanufacturing Challenges

The China Biopharmaceutical Boom Since China's Reform and Opening Up policy in 1978, the country has propelled unprecedented business and industry growth. In the light of its rising economy, biotech has started to grow at an explosive rate in China within the past few years. The industry is

Phase stabilization of a relativistic backward wave oscillator by controlling the cathode characteristics for a slowly rising voltage pulse

We found that the start time in microwave generation of a relativistic backward wave oscillator (RBWO) for a slowly rising voltage pulse demonstrates a large jitter, which can be explained by the spread of explosive electron emission thresholds and plasma formation rates of the explosive emission cathode, and this large jitter is reduced greatly by a weak external RF signal. So, the effects of the emission threshold and plasma formation rate on the oscillation start time of a single RBWO and on the phase synchronization in two parallel RBWOs are investigated using particle-in-cell simulations. The 2D simulations show that a larger emission threshold and a faster plasma formation rate lead to a shorter start time due to the stronger shock excitation provided by the sharper beam current leading edge. For some special emission thresholds, the start time is abnormally long, which is due to the generation of other frequencies because of the shock excitation. The 3D simulations illustrate that with a larger emission threshold and a faster plasma formation rate, phase synchronization can be obtained in two parallel RBWOs even for a large voltage rise time. Therefore, we expect that by choosing the appropriate cathode emission threshold and plasma formation rate, it is possible to realize phase stabilization of an RBWO for a slowly rising voltage pulse even without an external RF signal.

Cosmic ray transport and radiative processes in nuclei of starburst galaxies

AbstractThe high rate of star formation and supernova explosions of starburst galaxies make them interesting sources of high-energy radiation. Depending on the level of turbulence present in their interstellar medium, the bulk of cosmic rays produced inside starburst galaxies may lose most of their energy before escaping, thereby making these sources behave as calorimeters, at least up to some maximum energy. Contrary to previous studies, here we investigate in detail the conditions under which cosmic ray confinement may be effective for electrons and nuclei and we study the implications of cosmic ray confinement in terms of multifrequency emission from starburst nuclei and production of high-energy neutrinos. The general predictions are then specialized to three cases of active starbursts, namely, M82, NGC 253, and Arp220. Both primary and secondary electrons, as well as electron–positron pairs produced by gamma-ray absorption inside starburst galaxies are taken into account. Electrons and positrons produced as secondary products of hadronic interactions are found to be responsible for most of the emission of leptonic origin. In particular, synchrotron emission of very high energy secondary electrons produces an extended emission of hard X-rays that represents a very interesting signature of hadronic process in starburst galaxies, potentially accessible to current and future observations in the X-ray band. A careful understanding of both the production and absorption of gamma-rays in starburst galaxies is instrumental to the assessment of the role of these astrophysical sources as sources of high-energy astrophysical neutrinos.

Merkle Based Cryptographic Tree for Preventing Hash Collisions in Data Deduplication Mechanism on Servers

Due to the explosive rise in Digital Data content, the rise in the demand of new storage and network equipment is getting common with an increasing need for more cost-effective use of storage and network bandwidth for data transfer. Cloud services are also growing at an explosive rate as it provides cost efficient architectures. Such cloud architectures provide transmission and storage in multi user environment and works usually on pay per use model we only have a need to pay for what we use. For saving resources on cloud environment many cloud service provider use Data Duplication eradication mechanism. Here, Our approach is focusing on the Merkle Tree approach for eradication of Data Duplication.

Numerical Study on the Explosive Effect of RDX-based Aluminized Explosives on Stiffened Plates

The finite element software LS-DYNA was used to numerically investigate the damage of stiffened plates due to underwater explosive loads provided by RDX-based aluminized explosives. A finite element analysis model of fluid-solid coupling was established in order to study the elastoplastic dynamic buckling behavior of a stiffened plate structure. The effects of the RDX-based aluminized explosive energy release rate, shockwave energy, bubble energy and shockwave pressure on damage are discussed. A connection is established between aluminum content, the energy output of the underwater explosion and the response of the stiffened plate.

Explosion characteristics for Li-ion battery electrolytes at elevated temperatures.

Li-ion batteries are used in electronic devices and electric cars, yet they create safety concerns due to the possibility of the release of combustible materials. The electrolyte, one of the main components in a Li-ion cell, consists of organic carbonates. Venting and thermal runaway release organic carbonates and when mixed with air, it can result in fires and explosions. A 20-liter explosion sphere was used to determine the explosion characteristics for three typical carbonates used in electrolytes, at 373 K, and 100 kPa absolute pressure. The explosion pressure and the maximum rate of explosion pressure rise are presented for the carbonates and for hydrogen, methane, and propane, and the explosive limits for the carbonates are also identified at the same conditions. This allowed a comparison of the explosion characteristics for the carbonates with those for hydrogen, methane, and propane. Theoretical calculations gave a higher explosion pressure than that from the experimental results most likely due to losses in the hydrocarbon experiments. The carbonates analyzed have very similar explosion pressures and rate of explosion pressure rise as propane. The explosion characteristics found for the three carbonates can be used in future consequence and risk assessments for Li-ion battery installations.

Altered risky decision making in patients with early non-affective psychosis.

Abnormal risky decision making may represent an important factor contributing to functional impairment in psychotic disorders. Previous research revealed impaired decision making under risk in patients with chronic schizophrenia. However, risky decision making is under-studied in the early course of illness. We examined risky decision making in 33 patients with early non-affective psychosis and 32 demographically matched controls, using two well-validated experimental paradigms, balloon analogue risk task (BART) and Risky-Gains task (RGT), which modeled and assessed actual risk-taking behaviors in deliberative and time-pressured decision-making situations, respectively. Our results showed that patients exhibited suboptimal decision making on the BART and were more risk averse than controls by having fewer average balloon pumps in non-burst trials, lower explosion rate and lower total points gained. On the RGT, patients also behaved more conservatively than controls, with lower overall rate in choosing the risky option. Intriguingly, patients performed comparably to controls in adjusting risk-taking pattern following punished trials, suggesting relatively preserved sensitivity to punishment in early psychosis. Risk-taking measures showed no significant correlations with any symptom dimensions, impulsivity traits, cognitive functions or antipsychotic treatment after correcting for multiple comparisons. This study is the first to investigate risk-taking propensity in early psychosis based on BART/RGT performance, and consistently indicate that patients with early psychosis displayed altered risky decision making with increased risk aversion relative to healthy participants. Further investigation is warranted to clarify the longitudinal course of aberrant risky decision making and its relationship with functional outcome in early psychosis.

Disruption of Long-Term Effusive-Explosive Activity at Santiaguito, Guatemala

A comprehensive understanding of the dynamic evolution of active volcanic systems requires extensive sets of geophysical and geological data to fully constrain and understand shifts in eruptive behavior. The Santiaguito dome complex, Guatemala, is a remarkable example of an open-vent volcanic system where continuous eruptive activity has historically been characterized by cycles of effusion and frequent, small to moderate, gas-and-ash explosions. During 2015-2016 the volcano experienced a rapid intensification of activity including large vulcanian explosions, frequently accompanied by pyroclastic density currents. Here we present a chronology of the eruptive activity at Santiaguito from November 2014 - May 2017, compiled from field observations (visual and thermal) and activity reports. We also present seismic and acoustic infrasound data collected during the same period, the longest and largest dataset collected at Santiaguito to date. Three major phases of eruptive activity took place during the study period. The first phase was consistent with the long-term eruptive behavior reported at Santiaguito by previous studies: lava effusion simultaneous with small (\textless1 km plume height), regular (25-200 minute intervals), gas-and-ash explosions. The second phase from July 2015 to September 2016 was defined by large (\textless5-7 km plume height) vulcanian explosions at irregular intervals and often accompanied by pyroclastic density currents. The third phase was marked by a return to effusive activity in October 2016 interspersed by small, gas-rich explosions. Over 6000 explosive events were recorded by seismic and infrasound during the study period and clearly delineate the three phases of activity at the volcano. Furthermore, we present the first documented geophysical evidence of explosion blast waves and volcano-tectonic earthquake swarms at Santiaguito. An important implication of observations is that negative trends in explosion rates at silicic lava dome eruptions cannot be used alone as an indicator of future weaker activity and reduced risk. The dataset introduced here will serve as the foundation for future studies of the long-lived effusive eruption and rapid transitions to explosive volcanic activity at Santiaguito dome complex.

Joint Energy Efficient Subchannel and Power Optimization for a Downlink NOMA Heterogeneous Network

Non-orthogonal multiple access (NOMA) has been considered as a key technology in the fifth-generation mobile communication networks due to its superior spectrum efficiency. Since the heterogeneous network has been emerged to satisfy users' explosive data rate requirements and large connectivity of mobile Internet, implementing NOMA policy in heterogeneous networks (HetNets) has become an inevitable trend to enhance the 5G system throughput and spectrum efficiency. In this paper, we aim to maximize the entire system energy efficiency, including the macrocell and small cells, in a NOMA HetNet via subchannel allocation and power allocation. By considering the co-channel interference and cross-tier interference, the energy efficient resource allocation problem is formulated as a mixed integer nonconvex optimization problem. It is challenging to obtain the optimal solution; therefore, a suboptimal algorithm is proposed to alternatively optimize the macrocell and the small cells resource allocation. Specifically, convex relaxation and dual-decomposition techniques are exploited to optimize the subchannel allocation and power allocation. Moreover, optimal closed-form power allocation expressions are derived for small cell and macrocell user equipments by the Lagrangian approach. Simulations results show that the proposed algorithms can converge within ten iterations and can also attain higher system energy efficiency than the reference schemes.