Loose Mass Research Articles

Assessing the Effects of Fuel Based Lighting: The Case of Kerosene Use and Disasters in Nigeria

Fuel based lighting made up of kerosene continues to find essential use in West Africa. In Nigeria where tens of millions regularly use kerosene, adverse environmental health effects remain widespread much of the time given the mixed results. These include rising mortality and morbidity often associated with fire hazards from kerosene explosions, destruction of properties, burns, compromised vision, indoor air pollution, asthma and the disproportionate exposure of infants and women to the risks of recurrent kerosene hazards. With hospital emergency cases involving complications from kerosene hazards on the rise, adulterated products in the face of loose regulations and mass poverty has surged over the years. In all these, very little research exists to assess the risks from fuel lighting incidents and their impacts from a mix scale perspective using GIS. Accordingly, this paper analyzes the growing risks from kerosene disasters in Nigeria. Emphasis is on the issues, the trends, factors and impacts using mix scale techniques of GIS and descriptive statistics to map and track the trends spatially. Preliminary results using descriptive statistics reveal kerosene hazards in the form of fatalities through household explosions as well as health and environmental risks. Just as impact analysis identified pollution threats, the GIS mapping pinpointed the spatial dispersion of the risks and elements associated with kerosene hazards. With all these attributed to several elements from ineffective policy to economic conditions, the paper offered several remedies consisting of the need for education and enlightenment campaign, coupled with improved emergency response to fire hazards and the strengthening of policy. In highlighting the extent of kerosene hazards in the country, there is opportunity for resource managers and decision-making to build from it and design proactive measures to mitigate future disasters for the safety of citizens.

Influence of Shape and Orientation of Grinding Grains on Their Cutting Capacity

The issues of the influence of orientation and the shape of abrasive grains on one of their most important operational characteristics - cutting ability, and also on cutting properties of tools made of them, are considered in the article. Modern approaches to cutting capacity assessment, of both single grains, and loose abrasive mass are analyzed. The original method for the assessment of cutting capacity of a single grinding grain fixed in a rotating disk, implemented in surface grinding, is presented. The experimental data of the dependence of the cutting capacity on the shape and the orientation angle of the grinding grains are presented. In addition, the influence of the shape factor of the flap grinding wheel grains on its cutting capacity is shown. Practical recommendations on the application in practice of various varieties of grinding grains are proposed.

Thermoreversible crystallization-driven aggregation of diblock copolymer nanoparticles in mineral oil.

A poly(behenyl methacrylate)37 (PBeMA37) macromolecular chain transfer agent is utilized for the reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate (BzMA) directly in mineral oil at 90 °C. Polymerization-induced self-assembly (PISA) occurs under these conditions, yielding a series of sterically-stabilized PBeMA37-PBzMA x diblock copolymer spheres of tunable diameter as confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies. Rheological studies indicate that a relatively transparent, free-flowing, concentrated dispersion of non-interacting 32 nm PBeMA37-PBzMA100 spheres at 50 °C forms a turbid, paste-like dispersion on cooling to 20 °C. Turbidimetry and differential scanning calorimetry (DSC) studies conducted on solutions of PBeMA37 homopolymer in mineral oil suggest that this switchable colloidal stability is linked to crystallization-induced phase separation exhibited by this stabilizer block. Indeed, variable-temperature small-angle X-ray scattering (SAXS) indicates that a loose mass fractal network of strongly interacting spheres is formed on cooling to 20 °C, which accounts for this thermoreversible sol-gel transition. Moreover, SAXS, DSC and wide-angle X-ray scattering (WAXS) analyses indicate that the behenyl (C22H45) side-chains first form crystalline domains comprising adjacent stabilizer chains within individual spherical nanoparticles, with subsequent crystallization between neighboring nanoparticles leading to the formation of the mass fractal aggregates.

Spore germination and young gametophyte development of the endemic Brazilian hornwort Notothylas vitalii Udar & Singh (Notothyladaceae - Anthocerotophyta), with insights into sporeling evolution

ABSTRACT Notothylas vitalii is an endemic Brazilian hornwort species, easily identifi ed by the absence of pseudoelaters and columella, and the presence of yellow spores. Plant material was collected in Recife, Brazil, and the spores were sown onto Knop’s medium, germinating after thirty days only with the presence of light. Germination occurred outside the exospore, and only after the walls had separated into three or four sections did a globose sporeling initiate its development. Following longitudinal and transversal divisions, the initial loose mass of cells became a thalloid gametophyte, subsequently developing into a rosette-like juvenile thallus with fl attened lobes. Additional information concerning sporeling types in key genera of hornworts, such as and FoliocerosPhymatoceros, will be crucial for inferring the possible ancestral type and the evolution of this trait among hornworts. Our study supports the necessity of supplementary studies on sporeling development, combined with morphological and phylogenetic investigations, to help elucidate the evolution of the Anthocerotophyta and their distribution patterns.

Stability analysis of slope at a disused waste dump by two-wedge model

This study presents a large-scale failure of a disused external waste dump at an iron mine, one of the largest iron open pit mines in China. The dump is developed three beaches covering a total height of 130 m from the ground surface. It is dumped on an inclined clay layer with a maximum dip angle of 13° and average thickness of 9.34 m. The slide involved 7000000 m3 in volume of loose mass i.e. waste material, gravel and clay. In order to estimate the failure mode for slide, numerical simulation on failure mechanics of dump is performed by FLAC3D, and a physical model test on failure process of dump is carried out by the floor friction model. Results show that the waste dump slope moves horizontally along the clay layer in first. The horizontal movement of lower beaches results in the decrease of the shear resistance to lateral slide. Then, tensile cracks are generated in the top crest of the slope. Such failures with two planar slip surfaces have occurred at clay basement and through tensile cracks. With time, an obvious interface between lower block with large horizontal movement and upper block with large vertical movement is generated and then developed into the third planar slip surface. Sliding masses are divided by three slip surfaces into two wedges. A two-wedge model is established to evaluate stability for the waste dump. Factor of safety and failure mode calculated by the two-wedge method are nearly the same with those by strength reduction method.

Boosting the annihilation boost: Tidal effects on dark matter subhalos and consistent luminosity modeling

In the cold dark matter paradigm, structures form hierarchically, implying that large structures contain smaller substructures. These subhalos will enhance signatures of dark matter annihilation such as gamma rays. In the literature, typical estimates of this boost factor assume a concentration-mass relation for field halos, to calculate the luminosity of subhalos. However, since subhalos accreted in the gravitational potential of their host loose mass through tidal stripping and dynamical friction, they have a quite characteristic density profile, different from that of the field halos of the same mass. In this work, we quantify the effect of tidal stripping on the boost factor, by developing a semi-analytic model that combines mass-accretion history of both the host and subhalos as well as subhalo accretion rates. We find that when subhalo luminosities are treated consistently, the boost factor increases by a factor 2-5, compared to the typical calculation assuming a field-halo concentration. This holds for host halos ranging from sub-galaxy to cluster masses and is independent of the subhalo mass function or specific concentration-mass relation. The results are particularly relevant for indirect dark matter searches in the extragalactic gamma-ray sky.

Is Carbon Black a Suitable Model Colloidal Substrate for Diesel Soot?

Soot formation in diesel engines is known to cause premature engine wear. Unfortunately, genuine diesel soot is expensive to generate, so carbon blacks are often used as diesel soot mimics. Herein, the suitability of a commercial carbon black (Regal 250R) as a surrogate for diesel soot dispersed in engine base oil is examined in the presence of two commonly used polymeric lubricant additives. The particle size, morphology, and surface composition of both substrates are assessed using BET surface area analysis, TEM, and XPS. The extent of adsorption of a poly(ethylene-co-propylene) (dOCP) statistical copolymer or a polystyrene-block-poly(ethylene-co-propylene) (PS-PEP) diblock copolymer onto carbon black or diesel soot from n-dodecane is compared indirectly using a supernatant depletion assay technique via UV spectroscopy. Thermogravimetric analysis is also used to directly determine the extent of copolymer adsorption. Degrees of dispersion are examined using optical microscopy, TEM, and analytical centrifugation. SAXS studies reveal some structural differences between carbon black and diesel soot particles. The mean radius of gyration determined for the latter is significantly smaller than that calculated for the former, and in the absence of any copolymer, diesel soot suspended in n-dodecane forms relatively loose mass fractals compared to carbon black. SAXS provides evidence for copolymer adsorption and indicates that addition of either copolymer transforms the initially compact agglomerates into relatively loose aggregates. Addition of dOCP or PS-PEP does not significantly affect the structure of the carbon black primary particles, with similar results being observed for diesel soot. In favorable cases, remarkably similar data can be obtained for carbon black and diesel soot when using dOCP and PS-PEP as copolymer dispersants. However, it is not difficult to identify simple copolymer-particle-solvent combinations for which substantial differences can be observed. Such observations are most likely the result of dissimilar surface chemistries, which can profoundly affect the colloidal stability.

Precipitation of salts during capillary hoist in solutions in subsurface aeration zone

Series of experiments on seepage of water solutions of nickel and cobalt through an evaporation barrier in a porous loose rock mass is described. Evaporation intensity shows tendency toward linear decrease with time due to change of the rock mass porosity as a consequence of salt precipitation in the subsurface aeration zone. It is possible to control evaporation intensity by redistributing vertical zonality of precipitate in the subsurface zone. The authors find mechanism of precipitated salt distribution in subsoil.

Terahertz Spectroscopy for Real-Time Monitoring of Water Vapor and CO Levels in the Producer Gas From an Industrial Biomass Gasifier

In this paper, we present a study of THz transmission spectroscopy as a novel tool for the monitoring of the steam and CO contents of the raw gas from industrial biomass gasifiers. A THz gas spectrometer with a frequency range of 300-500 GHz was designed and constructed. Proof-of-principle testing was performed at laboratory conditions using mixtures of different gases at high temperatures (600-700 K). The results demonstrate the feasibility of applying strong rotational water vapor lines at 448 and 383 GHz, so as to obtain reliable online measurements of water vapor with an absolute precision of about 0.2 vol.% for the current device. CO lines were identified at 461 and 346 GHz, facilitating measurement of this gas. The gas spectrometer was integrated into an industrial gasifier and boiler, and its performance was tested in terms of online measurements of steam and CO in the hot raw gas and flue gases under real-life conditions. Considering the error intervals, the results are in complete agreement with data acquired by solving loose mass balances around the system. The onsite experiments demonstrate that THz gas spectroscopy is a promising tool for fast, robust, and reliable monitoring in industrial applications.

Dust composition and mass-loss return from the luminous blue variable R71 in the LMC

We present an analysis of mid-and far-infrared (IR) spectrum and spectral energy distribution (SED) of the LBV R71 in the LMC.This work aims to understand the overall contribution of high-mass LBVs to the total dust-mass budget of the interstellar medium (ISM) of the LMC and compare this with the contribution from low-mass asymptotic giant branch (AGB) stars. As a case study, we analyze the SED of R71. We compiled all the available photometric and spectroscopic observational fluxes from various telescopes for a wide wavelength range (0.36 -- 250\,$\mu$m). We determined the dust composition from the spectroscopic data, and derived the ejected dust mass, dust mass-loss rate, and other dust shell properties by modeling the SED of R71. We noted nine spectral features in the dust shell of R71 by analyzing Spitzer spectroscopic data. Among these, we identified three new crystalline silicate features. We computed our model spectrum by using 3D radiative transfer code MCMax. Our model calculation shows that dust is dominated by amorphous silicates, with some crystalline silicates, metallic iron, and a very tiny amount of polycyclic aromatic hydrocarbon (PAH) molecules. The presence of both silicates and PAHs indicates that the dust has a mixed chemistry. We derived a dust mass of 0.01 M$_\odot$, from which we arrive at a total ejected mass of $\approx$ 5 M$_\odot$. This implies a time-averaged dust mass-loss rate of 2.5$\times$10$^{-6}$ M$_\odot$\,yr$^{-1}$ with an explosion about 4000 years ago. We assume that the other five confirmed dusty LBVs in the LMC loose mass at a similar rate, and estimate the total contribution to the mass budget of the LMC to be $\approx$ 10$^{-5}$ M$_\odot$\,yr$^{-1}$, which is comparable to the contribution by all the AGB stars in the LMC. Based on our analysis on R71, we speculate that LBVs as a class may be an important dust source in the ISM of the LMC.

Understanding fracture behaviour of PGA reactor core graphite: perspective

Magnox reactors are cooled by carbon dioxide gas. The pile grade A (PGA) graphite moderator bricks in the reactor core loose mass and become more porous during service due to the radiolytic oxidation caused by energy deposition, mainly gamma radiation. In addition, neutron irradiation brings about strengthening by irradiation hardening and dimensional change. In this perspective, experimental data related to the attendant microstructural changes and the associated initiation and propagation of cracks within the graphite are revisited. These results are compared with the predictions of multiscale finite element modelling based upon an idealised microstructure. The discussion considers the quasi-brittle characteristics of the PGA graphite over a range of service exposure conditions.

The formation of runoff-generated debris flow in Southwestern of China: take Gangou as an example

In the mountain area of Southwestern China, there are large quantities of runoff-generated debris flows that are threatening the local people and facilities seriously. Gangou is a typical runoff-generated debris flow; its source is old deposit from floods and the debris flows downstream of the channel. On June 30, 2005, Gangou occurred debris flow, the debris flow destroying the road, the communications facilities and the farmland at the gully mouth. Unlike the formation mechanisms of other debris flows, the formation of 2005 debris flow in Gangou has its distinctive characteristics as follows. (1) The supply of the loose sources is intensive and distribute near the mouth of the gully; it is rare to see any debris flow initiate at such a lower location. (2) The debris flow finishes its initiation, flow and deposition around the 700-m-long channel, accompanied with the blocking process in the gully when the debris flow ran out; however, 10 min later, it releases and amplifies the peak flow about three times. (3) The topographic condition of the basin does not contribute much to the formation of the 2005 debris flow; instead, its formation is the result of the co-effort of continuous rainfall and a short-time heavy rainfall. In other words, the previous cumulative precipitation enables the moisture content of the soil on the right bank of the gully to reach saturation; then the soil slides into the channel under the action of the heavy rainfall at a later time. Meanwhile, the heavy rainfall accelerates the formation of gully run-off and initiates the loose mass in the channel from slide, thus forming the debris flow.

New Technology and Mechanism Study of the Bearing Enhancement of Broken Rock Zone in Underground Rock Roadway

Treating surrounding rock as absolutely loose mass helps to determine positions of the four key reinforced points in roadway, in other words, they are juncture locations between 45 degrees angle directions of two arch haunches and two footwalls. Surrounding rock deformation can be effectively controlled with the help of reinforcement on key reinforced points, furthermore, it is possible to save lots of supporting materials, in short, it is a very effect way. New technology proposed in this paper what is about stable augmentation has deeply unearthed important effect of anchor in floor of roadway, it argues that anchor in floor has quadruplex efficacies: transferable effect of surrounding rock stress, displacement boundary effect, decreasing equivalent stress of basic angle area and the inverted wedge effect, so it can suppress floor heave effectively, and this lays a solid foundation for roadway stability. Article deeply analyzed basic mechanism about deformation of roadway under loading, exposed essentiality of roadway support, and provided important theoretical basis for floor heave control emerged more and more frequently in deep mine roadway. Key words: broken rock zone, bolt support, floor heave, equivalent stress

A Novel Industrial Wireless Sensor Network for Condition Monitoring and Fault Diagnosis of Electrical Machines

A novel industrial wireless sensor network (IWSN) for condition monitoring and fault diagnosis of electrical machines is presented, in which on-sensor fault diagnosis based on principal component analysis is explored to address the tension between the high system requirements of electrical machine monitoring and the resource constrained characteristics of IWSN sensor nodes. The prototype system is evaluated with a single phase induction motor monitoring system. Normal motor working conditions and two types of motor faults, ie. loose feet and mass imbalance, are monitored to validate the feasibility of the proposed system. The results show that using on-sensor fault diagnosis can reduce transmission data by 99.8%, decrease energy consumption, and prolong node lifetime from 106 to 153 h, an increase of 44%. The experimental results also indicate that the proposed approach has high fault diagnosis accuracy.

A novel industrial wireless sensor network for condition monitoring and fault diagnosis of electrical machines

A novel industrial wireless sensor network (IWSN) for condition monitoring and fault diagnosis of electrical machines is presented, in which on-sensor fault diagnosis based on principal component analysis is explored to address the tension between the high system requirements of electrical machine monitoring and the resource constrained characteristics of IWSN sensor nodes. The prototype system is evaluated with a single phase induction motor monitoring system. Normal motor working conditions and two types of motor faults, ie. loose feet and mass imbalance, are monitored to validate the feasibility of the proposed system. The results show that using on-sensor fault diagnosis can reduce transmission data by 99.8%, decrease energy consumption, and prolong node lifetime from 106 to 153 h, an increase of 44%. The experimental results also indicate that the proposed approach has high fault diagnosis accuracy.

Study of the Three-Dimensional Global Limit Equilibrium Method Applied to the Stability of Rock Slope

Amending the normal stress over the slip surface based on the stress field by numerical analysis, applying the three-dimensional global limit equilibrium method to the stability analysis of tension-slackened rock mass in the right bank of Yagen hydropower station. Stability analysis shows that if do not take any measures, the loose rock mass stability can cater to the Specification demand, but some small sliders is in the limit state under the water and earthquake condition, if use the cutting slope and unloading scheme, the whole loose rock mass and the all small sliders can meet the Specification standard stability requirements.

Body mass and growth of overwintering brown trout in relation to stream habitat complexity

AbstractIn winter, juvenile salmonids hide within the substrate during the day and emerge to feed on drifting invertebrates at night. In channelized streams, where the streambed heterogeneity has been artificially reduced, suitable microhabitats (low‐flow refugia) may be in short supply. Therefore, restoration of stream habitat by enhancement structures might improve the overwintering conditions of juvenile salmonids. We used a set of artificial streams to test whether individually‐marked juvenile brown trout of two age‐classes (age‐0 and age‐1 trout) loose mass during the winter differently in channelized and semi‐natural streams. Fish of both age‐classes lost mass early in the winter (November to January), but age‐0 fish in the channelized streams lost more of their initial mass than did the restored‐stream fish (ca. 10% vs. 2.5% on average, respectively). They then exhibited zero‐growth in both treatments in late winter (January to April), and by early spring (May), the channelized‐stream fish had completely caught up for their greater initial mass loss. In control tanks where the fish were fed continuously, age‐0 trout exhibited zero‐growth from November to January, then gaining mass constantly through the rest of the experiment. Significant time*treatment interaction was also detected for age‐1 trout, but all differences were caused by the faster growth of fish in the control tanks, whereas the two channel treatments did not differ significantly. The shortage of suitable sheltering sites in the channelized streams apparently intensified competition and caused greater initial mass loss in age‐0 trout. Furthermore, growth compensation exhibited by juvenile trout may have negative impacts on the long‐term fitness of individuals. Therefore, by increasing the amount of sheltering sites, in‐stream restoration may have potential to enhance the overwintering success of juvenile salmonids. Copyright © 2010 John Wiley & Sons, Ltd.

Experimental Study on Highway Tunnel Surrounding Rock Reinforced by Small Pipe Pre-Grouting

Small pipe of staggered by length leading-drilling and grouting support technology was adopted for per-reinforcement of Lion-shaped Tunnel typeII rock, cement paste filled into loose rock mass rock fracture for adglutinate broken rock into a integrality, thus enhance the coherence and solidity of rock. Thesis introduced process flow of small pipe drilling grouting, grouting equipment, grouting parameters selection and practical applications. Through tunnel deformation monitoring and analysis, grouting reinforcement has achieved very good effect.

Nakamura Spectral Ratio Characteristics of Microseism Signal Induced by Relieve-Shot

Abstract By weakening the strength of coal-rock masses and releasing large elastic energy accumulated, relieve-shot can reduce the rockburst tendency. The accurate assessment of the relieve-shot effect has an important guiding significance for dynamic prevention of rockburst. Based on the basic supposition of Nakamura method, Nakamura spectral ratio model of microseismic (MS) signal propagation of relieve-shot was effectively established. The Nakamura spectral ratio can reveal the predominant resonance frequency evolution rule of coal-rock mass after relieve-shot being discovered. Through the relieve-shots implemented in 7206 driving working face of Sanhejian coal mine (SCM), Nakamura spectral ratios of relieve-shot MS signals were analyzed in detail. The bigger Nakamura spectral ratio is, the higher the stress in coal and rock materials is. High dominant frequency of Nakamura spectrum ratio indicates loose and cracked rock and coal mass where elastic energy is released effectively, thereby high resonant frequency can be created, which suggests the effect of pressure release blasting is desirable. Meanwhile, another relieve-shot effect is effectively checked by measuring drilling bits on spot. Therefore, the correlation between Nakamura spectral ratio and MS signal predominant frequency can evaluate the relieve-shot effect more accurately.

NUMERICAL TREATMENT OF THIN ACCRETION DISK DYNAMICS AROUND ROTATING BLACK HOLES

In the present study, we perform the numerical simulation of a relativistic thin accretion disk around the nonrotating and rapidly rotating black holes using the general relativistic hydrodynamic code with Kerr in Kerr–Schild coordinate that describes the central rotating black hole. Since the high energy X-rays are produced close to the event horizon resulting the black hole–disk interaction, this interaction should be modeled in the relativistic region. We have set up two different initial conditions depending on the values of thermodynamical variables around the black hole. In the first setup, the computational domain is filled with constant parameters without injecting gas from the outer boundary. In the second, the computational domain is filled with the matter which is then injected from the outer boundary. The matter is assumed to be at rest far from the black hole. Both cases are modeled over a wide range of initial parameters such as the black hole angular momentum, adiabatic index, Mach number and asymptotic velocity of the fluid. It has been found that initial values and setups play an important role in determining the types of the shock cone and in designating the events on the accretion disk. The continuing injection from the outer boundary presents a tail shock to the steady state accretion disk. The opening angle of shock cone grows as long as the rotation parameter becomes larger. A more compressible fluid (bigger adiabatic index) also presents a bigger opening angle, a spherical shock around the rotating black hole, and less accumulated gas in the computational domain. While results from [J. A. Font, J. M. A. Ibanez and P. Papadopoulos, Mon. Not. R. Astron. Soc.305 (1999) 920] indicate that the tail shock is warped around for the rotating hole, our study shows that it is the case not only for the warped tail shock but also for the spherical and elliptical shocks around the rotating black hole. The warping around the rotating black hole in our case is much smaller than the one by [J. A. Font, J. M. A. Ibanez and P. Papadopoulos, Mon. Not. R. Astron. Soc.305 (1999) 920], due to the representation of results at the different coordinates. Contrary to the nonrotating black hole, the tail shock is slightly warped around the rotating black hole. The filled computational domain without any injection leads to an unstable accretion disk. However much of it reaches a steady state for a short period of time and presents quasi-periodic oscillation (QPO). Furthermore, the disk tends to loose mass during the whole dynamical evolution. The time-variability of these types of accretion flowing close to the black hole may clarify the light curves in Sgr A*.