Form Of Wedge Research Articles

Mesoscale Impacts on Cold Season PM<sub>2.5</sub> in the Yukon Flats

Near-surface PM2.5 and meteorological observations were performed in three rural communities in the high latitude Yukon Flats valley at various times during the cold season (October to April). These data were synthesized with data from other meteorological sites, NCEP reanalysis and MAIAC retrieved aerosol optical depths data to analyze the role of mesoscale processes and radiation on air quality. Under weak large-scale forcing mountain-valley circulations develop that are driven by the differences in insolation. During the long dark nights, radiative cooling occurs in the near-surface layer of the mountain slopes of the Brooks, Ogilvie and White Mountains Ranges and at the bottom of the valley. Here surface-based inversions (SBI)—known as roof-top inversions—forms, while the cold air drains from the slopes. A frontal wedge forms when the cold air slides over the relatively colder air in the valley. Drainage of cold air from the Brooks Range governed the circulation and cold air pooling in the valley. Concentrations during times with and without SBI differed significantly (at 95% confidence) at two sites indicating that local emissions were the major contributor. At the site, which is closest to the mountains, concentrations marginally changed in the presence of inversions. At all sites, 24-h mean PM2.5 remained below the National Ambient Air Quality Standard.

Directed Network of Substorms Using SuperMAG Ground‐Based Magnetometer Data

AbstractWe quantify the spatiotemporal evolution of the substorm ionospheric current system utilizing the SuperMAG 100+ magnetometers. We construct dynamical directed networks from this data for the first time. If the canonical cross‐correlation between vector magnetic field perturbations observed at two magnetometer stations exceeds a threshold, they form a network connection. The time lag at which canonical cross‐correlation is maximal determines the direction of propagation or expansion of the structure captured by the network connection. If spatial correlation reflects ionospheric current patterns, network properties can test different models for the evolving substorm current system. We select 86 isolated substorms based on nightside ground station coverage. We find, and obtain the timings for, a consistent picture in which the classic substorm current wedge forms. A current system is seen premidnight following the substorm current wedge westward expansion. Later, there is a weaker signal of eastward expansion. Finally, there is evidence of substorm‐enhanced convection.

The frozen grounds processing with a bucketless bottom rotor

The analysis of special conditions of buildings construction and transport constructions in difficult geotechnical and severe climatic conditions has been given. It is necessary to have a special working facility for earth excavation implementation. The bucketless bottom rotor with destructive elements in the form of oblique wedges meets these requirements. It allows destroying frozen and strong grounds with the least power-intensive way. The calculation method of ground separation force by angular teeth on the basis of spatial representation of ground failure forces has been given. The calculations have been confirmed with natural experiments of an excavator on frozen grounds.

Preliminary Experimentation of Fast Neutron Radiography with D-T Neutron Generator at BARC

An experimental study on fast neutron radiography (FNR) has been carried out using a laboratory based D-T neutron generator facility at Bhabha Atomic Research Centre (BARC) and initial results are presented. The aim was to develop an FNR system with a moderate intensity neutron source for imaging of specimen containing mixed low-Z and high-Z materials. The experimental set-up consists of a D-T neutron generator, collimator and an EMCCD camera based imaging system. Experiments were carried out with the neutron generator having a source strength of about 2 × 109 n/s and source spot size of 20 mm. To obtain optimum image quality with such a moderate neutron yield, a collimator has been designed having an inlet aperture of 10 mm and an L/D of 43. The imaging system was kept at an optimum distance from the collimator and various test samples of materials ranging from low Z to high Z were imaged. Thick samples in step wedge form, hole features in step wedge of polyethylene, mild steel and lead were imaged and analysed. Also a test sample of a low Z material (HDPE) with a hole placed behind a thick Pb was imaged to study the effect of thickness of high Z material on image quality with fast neutrons. The initial results emphasizes that a moderate yield D-T neutron generator based fast neutron radiography system with EMCCD camera could be deployed for field applications yielding moderate image quality to obtain first hand information of the investigated samples.

Features of the Surface and Subsurface Waves Application for Ultrasonic Evaluation of Physicomechanical Properties of Solids. Part 1. Influence of the Geometrical Parameters

Application of surface and subsurface waves for control of objects with a double-layer structure allows to extend possibilities of diagnostics of their physico-mechanical properties. The purpose of work was to determine conditions and offer recommendations providing measuring of ultrasonic velocity and amplitude of the former modes in protective layers and in basis of object at one-sided access to its surface.The analysis of an acoustic path of a measuring system in relation to ultrasonic evaluation of the objects having the restricted sizes and the protective coating according to velocity data of the surface and subsurface waves propagation is made. On the basis of representations of beam acoustics the dependences connecting a wavelength of the excited surface and subsurface modes, thickness and width of a controlled object, acoustic base of a sounding are defined. There are to provide a condition leveling of the influence of an acoustical noise created by the reflected and accompanying waves on parameters of acoustic signal with the given quantity of oscillations in an impulse.The principle opportunity is shown and conditions for determination of velocity of subsurface body waves in the base material which is under a protective coating layer are established. For these purposes on the basis of use of the block of ultrasonic probes the optimum scheme of a sounding is offered and the analytical expression for calculation of required velocity considering varying of thickness of a covering is received.The method of acoustical measuring realized by a direct and reverse sounding of the objects with small aperture and angle probes was analysed and formulas for determination of speed of subsurface wave under protective layer of the wedge form have been got. An ultrasonic device is suggested for the excitationreception of subsurface waves with different speed in objects (on 20–35 %) using for the acoustic concordance of environments of metallic sound duct as a wedge. Possibility of leveling of interference in a protective layer to control efects in basis of material by a volume wave by creation of supporting echo-signal of longitudinal wave of the set frequency and entered normally to the surface of object was studied.

Determining EDS and EELS partial cross-sections from multiple calibration standards to accurately quantify bi-metallic nanoparticles using STEM

Spectroscopic signals such as EDS and EELS provide an effective way of characterising multi-element samples such as Pt-Co nanoparticles in STEM. The advantage of spectroscopy over imaging is the ability to decouple composition and mass-thickness effects for thin samples, into the number of various types of atoms in a sample. This is currently not possible for multi element samples using conventional ADF quantification techniques alone. With recent developments in microscope hardware and software, it is now possible to acquire the ADF, EDS and EELS signals simultaneously and at high speed. However, the methods of quantifying the signals emitted from the sample vary greatly. Most approaches use pure-element standards in the form of needles, nanoparticles and wedges to quantify the spectroscopic signal into either partial scattering cross-sections, zeta-factors or k-factors. But self-consistency between the different methods has not been verified and the units of the quantification are not standardised. We present a robust approach for measuring and combining ADF, EDS and EELS signals using needle and nanoparticle standards in units of the partial scattering cross-section. The partial scattering cross-section allows an easy interpretation of the signals emitted from the sample and enables accurate atom-counting of the sample.

Influence of the Spatial Model of Lithospheric Plates on an Initial Earthquake

The boundary-value problem for a block structure consisting of an elastic half-space that occupies the lower part of a Cartesian coordinate system and interacts with two block elements in the form of unbounded wedges with right angles at the vertices is considered. The horizontal boundaries of the wedges are rigidly connected with the half-space boundary, and vertical ones are parallel planes. We consider the antiplane problem for cases where the distance between the vertical boundaries of block elements is present or absent. By the example of a three-dimensional problem degenerating into a two-dimensional one, it is shown that an initial earthquake is possible, like in the case of using Kirchhoff plates instead of three-dimensional block elements.

The mechanism of roadway deformation in conditions of laminated rocks

Abstract The high stress condition of the rock requires a change in the approach to the design and usage of roadway support. It is necessary to take into account the mutual deformations of the support – rock mass system, as well as the peculiarities of the deformation mechanism of the roadway rock contour. The purpose of this paper is to analyze the mechanism of roadway deformation in conditions of laminated rocks and deep mine. A simple approach to the analysis of stress distribution around the roadway that includes Kirsch equations is used. It is shown that the strength anisotropy determines the weakest place in the roadway contour, where destruction takes place. The deformation of the rock around a single roadway occurs in the form of extrusion wedges of laminated rocks in the roof and floor is also show. The results of in-situ observations over the displacement of the roof and the floor of deep mine roadways are analyzed. The linear correlation between roof sag and floor heave is established. It is stressed that roof sag must be prevented in order to effectively counteract the extrusion of the floor rock.

Surgical treatment of gastrointestinal stromal tumors of the stomach: current status and future perspective.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, with the majority found in the stomach. Surgical resection of the primary gastric GISTs with complete resection margin has been the forefront of curative treatment. The indications for surgical resection are usually related to symptomatic gastric GISTs at presentation. Primary gastric GISTs resection performed conventionally through an open surgery can now be frequently achieved by minimal invasive surgery with similar oncological outcome. Surgeon's selection of the type of surgical techniques such as open, laparoscopic and endoscopic resections depends on the site, size and local invasion of gastric GISTs to the adjacent organ. Similarly those factors dictate the extent of gastric resections in the form of wedge, partial or total gastrectomy. All these inherent tumor factors (size and mitotic index), patient factors (older age, male) and surgical factors (incomplete resection margin, tumor rupture or spillage) play an important role in stratifying the malignant potential risk of primary gastric GISTs and their chances of recurrence. The understanding of gene mutation driving the growth of GISTs and the discovery of tyrosine kinase inhibitors (TKIs) has altered the surgical management of advanced and metastatic GISTs. Multi-modal therapy incorporating the surgical resection of GISTs and utilizing the molecular targeted therapy in the adjuvant, neoadjuvant and palliative settings can offer optimal personalized outcome and prolong patient's overall survival (OS).

Stratigraphy, mineralogy and depositional environment of the evaporite unit in the Aşkale (Erzurum) sub-basin, Eastern Anatolia (Turkey)

The study area is situated in the Aşkale sub-basin where the Early-Middle Miocene aged Aşkale Formation was deposited in a shallow marine to lagoonal environment, and consists of interstratifications of clastic sediments, carbonates and evaporites. The successions of the Aşkale Formation can be divided into four main members interfingering with one another both vertically and laterally, and composed of the sandstone-mudstone-limestone member, the evaporite member, the gravelstone-sandstone-mudstone intercalations and the limestone member. The evaporite unit comprises of secondary gypsum lithofacies formed by hydration of precursor anhydrite, anhydrite, gypsum-bearing limestone and claystone in the form of wedges and lenses. Massive, nodular, nodular-banded, laminated and laminated-banded gpysum lithofacieses in addition to chicken-wire and rare entrolithic structures were described, indicating a sabhka or a shallow water depositional environment. Alabastrine and porphyblastic textures of gypsum were identified within the all lithofacieses with abundant amount of anhydrite relics. Additionally, saponite and illite/smectite, calcite and dolomite, celestite, epsomite were also observed. Successions of the Aşkale Formation were deposited in stable subtropical climatic conditions within rapidly subsiding sub-basin resulted in conversion of sub-basin to shallow platform and even in lagoon environment.

Microstructure of quenched doped InSb

Magnetic characterization results indicate that, after liquid quenching, InSb samples doped with manganese, manganese + zinc, and manganese + cadmium are magnetic semiconductors. According to microstructural analysis data, polished sections of these materials demonstrate surface order: the grains have the form of wedges directed from the periphery of the section to its center, occupy essentially the entire surface of the section, and have low-angle boundaries with dislocation outcrops on the sample surface. According to X-ray diffraction data, quenched doped InSb samples are free of impurity phases and have preferential crystallographic orientations. Analysis of the present experimental data leads us to conclude that the surfaces of metallographic specimens of doped InSb are sections through textures whose orientation—under given quenching conditions—depends on the dopant composition.

Mechanism and Control of Eccentric Wear of Sucker Rod

The issue of eccentric wear of sucker rod is not only reduce the strength of the sucker rod that results to sucker rod breaking, but also wear out the pipe leading to leakage of tubing, which impact the regular production of the well. This paper aims at the popular issue in-site, analyze the factors such as wellbore deviation, stroke and fluid viscosity, tested the effect of water content, submergence on the eccentric wear by the laboratory experiment. The mechanism of eccentric wear of sucker rod is studied based on the factors impact the deformation under the stress and displacement constraints. An advanced technique is proposed to prevent eccentric wear based on the theory of hydraulic lubrication theory. It can make wedge form gap formed between sucker rod and tubing with the special tools, so that prolong the life of the well.

Heat transfer and fluid flow analysis of artificially roughened ducts having rib and groove roughness

Artificially roughness is one of the well known methods of enhancing heat transfer from the heat transfer surface in the form of repeated ribs, grooves or combination of ribs and groove (compound turbulators). The artificial roughness produced on the heat transferring surface is used in cooling of gas turbine blades, nuclear reactor, solar air heating systems etc. Solar air heaters have wide applications in low to moderate temperature range, namely, drying of foods, agricultural crops, seasoning of wood and space heating etc. Solar air heaters have low value of convective heat transfer coefficient between the working fluid (air) and the heat transferring surface, due to the formation of thin laminar viscous sub-layer on its surface. The heat transfer from the surface can be increased by breaking this laminar viscous sub layer. Hence, in the present work compound turbulators in the form of integral wedge shaped ribs with grooves are used on the heat transfer surface, to study its effect on the heat transfer coefficient (Nusselt number) and friction factor in the range of Reynolds number 3,000–18,000. The roughness produced on the absorber plate forms the wetted side of upper broad wall of the rectangular duct of solar air heater. The relative groove position (g/p) was varied from 0.4 to 0.8 and the wedge angle (Φ) was varied from 10° to 25°, relative roughness pitch (p/e) and relative roughness height (e/D) was maintained as 8.0 and 0.033 respectively. The aspect ratio of the rectangular duct was maintained as 8. The Nusselt number and friction factor of the artificially roughened ducts were determined experimentally and the corresponding values were compared with that of smooth surface duct. It is observed that wedge-groove roughened surface shows more enhancement in heat transfer compared to only rib roughened surface arrangement. The investigation revealed that Nusselt number increases 1.5–3 times, while the friction factor increases two to three folds that of the smooth surface duct in the range of operating parameters. It is also observed that in rib–groove roughness arrangement with relative groove position of 0.65 shows the maximum enhancement in the heat transfer compared to the other rib-groove roughness arrangements. Statistical correlations for the Nusselt number and friction factor have been developed by the regression method in terms of the operating and roughness parameters. A program was also developed in MATLAB for the calculation of thermal efficiency and thermal effectiveness. It was observed that the thermal efficiency is more for wedge angle of 15° and relative groove position of 0.65 and its value ranges from 42 to 73 %. The uncertainties in the measurements due to various instruments for the Reynolds number, Nusselt number, and friction factor have been estimated as ±3.8, ±4.54 and ±7.6 % respectively in the range of investigation made.

Layered WO3/TiO2 nanostructures with enhanced photocurrent densities

Layered WO3/TiO2 nanostructures, fabricated by magnetron sputtering, demonstrate significantly enhanced photocurrent densities compared to individual TiO2 and WO3 layers. First, a large quantity of compositions having different microstructures and thicknesses were fabricated by a combinatorial approach: diverse WO3 microstructures were obtained by adjusting sputtering pressures and depositing the films in form of wedges; later layers of TiO2 nanocolumns were fabricated thereon by the oblique angle deposition. The obtained photocurrent densities of individual WO3 and TiO2 films show thickness and microstructure dependence. Among individual WO3 layers, porous films exhibit increased photocurrent densities as compared to the dense layer. TiO2 nanocolumns show length-dependent characteristics, where the photocurrent increases with increasing film thickness. However, by combining a WO3-wedge type layer with a layer of TiO2 nanocolumns, PEC properties strikingly improve, by about two orders of magnitude as compared to individual WO3 layers. The highest photocurrent that is measured in the combinatorial library of porous WO3/TiO2 films is as high as 0.11 mA/cm2. Efficient charge-separation and charge carrier transfer processes increase the photoconversion efficiency for such films.

Anisotropy of porous silicon formation rate in p‐Si

AbstractWe studied the anisotropy of meso‐ and microporous silicon formation rate on curved surfaces and on flat samples. Experiments on anodization of model p++‐cylinders demonstrated that faceting appears on their lateral surface. This indicates that the etching rates vary between different crystallographic planes. Quantitative data on the etching‐rate anisotropy were obtained by anodization of wafers through a mask in the form of narrow wedges radiating from a center in all directions (wagon wheel mask). We examined the dependence of porous silicon formation rate anisotropy on current and Si doping. It was shown that for p++ substrates, in all anodization modes, the <100> direction corresponds to the maximum growth rate. The current affects the etching‐rate distribution among crystallographic directions: under low currents anisotropy of pore‐front propagation rate may be as high as 20%. An even stronger influence on the anisotropy characteristics is exerted by the substrate doping level. It was found for the first time that, for silicon with acceptor concentration NB ≈ 1017–1018 cm−3, the <111> axis becomes the fastest growth direction, and the <100> axis, by contrast, is transformed to the direction of the slowest pore‐front propagation. This phenomenon correlates with rotation of the optical axis in birefringent mesoporous silicon on passing from p++‐Si to p+‐Si, as is known from the literature.

A form of two-sided wedge with minimum sticking

Приведены результаты исследований и расчетные данные, свидетельствующие о том, что для уменьшения залипания рабочих органов культиватора-плоскореза-глубокорыхлителя форма рабочей поверхности лемеха должна быть криволинейной.

Form deviations of hot work tool steel 55NiCrMoV (52HRC) after face finish milling

At the beginning of article a 3D view of machined surface has been presented and correctness of form profiles registration on milling machine verified. A number of tool materials, recommended by producers for milling of hardened steel, were tested for wedge wear and form deviations. Components of the deviations coming from position changes of wedge corner due to its wear, deformation of machined system as well as tilt of face mill axis were compared. Comparisons were aimed at determining qualitative and quantitative impact of main factors on face milled surface form deviations so as to create models of their arising.

Three‐dimensional numerical models with varied material properties and erosion rates: Implications for the mechanics and kinematics of compressive wedges

We develop three‐dimensional mechanical models of a compressive wedge and investigate how the form and kinematics of the outboard wedge are affected by variation in initial topography, material properties, and erosion rate. Inclusion into the wedge of weaker, less dense material affects the form of the wedge, producing a region of steeper average slopes and higher topography while depriving the region further inboard of material. Enhanced erosion has a similar effect. The wedge attempts to replace the eroded material by focusing deformation. The result is a stepped region of lower topography within the outboard of the orogen. We observe that uplift velocities at three points in the orogen vary cyclically from near zero to ∼3 times the average uplift rate over cycles lasting on the order of 15–200,000 model years. Our models, along with analog models and some well‐dated examples from active orogens, suggest that transient accommodation of strain may be common. The cycles observed responded rapidly to changes in the amount of erosion imposed. Our models suggest that orogens may be driven by strong coupling between erosion and strain on temporal scales of 104–105 years and spatial scales comparable to the scale of the erosional perturbation. We compare our models to the Puli Embayment of west central Taiwan, a region of anomalous low topography and suggest that it presence may reflect the presence of weaker and more erodible sediments than those present along strike in the orogen.

Management of chronic recurrent temporomandibular joint dislocations: A retrospective study

The purpose of this study is to evaluate the clinical results of patients who received surgical treatment for chronic recurrent dislocations (CRD). In our clinical practice CRD patients were classified into 5 types depending upon their aetiology. These patients were treated by two different surgical techniques, eminectomy or augmentation of the eminence by autograft depending on their classification. Nineteen patients with CRD attended the clinic for surgical treatment. Patients were classified accordingly into 5 types of CRD. Eminoplasty was used in the treatment of twelve patients with type I and II disease. An oblique osteotomy of the eminence was carried out. Harvested chin graft was contoured to a wedge form and inserted tightly into the osteotomy site. The augmentation of the eminence was provided by an inlay cortical bone graft without using any of the conventional fixation materials. The remaining 7 patients with type III, IV and V disease were treated by eminectomy. The factors evaluated were pre- and post-operative maximal incisor opening, sex, age, number and type of previous operations, cause and type of the CRD, and the previous treatment of the patients. The survey is based on nineteen patients who were treated in the same department. Patients age ranged from 22 to 80 years. Females are dominated in the study. The follow-up period ranged from 1 to 12 years. Free excursions of the condyles were achieved in the patients treated by two different techniques. On the other hand, maximum interincisal openings were higher in the patients treated by eminectomy when compared with the patients who had eminoplasty. So far as the quality of life for the patients with CRD is concerned, the most appropriate technique (whether it be to confine the condyle or allow its free movement) to be employed should be decided by following an comprehensive evaluation of the patients' history.

Design of continuity processes of electrochemical finishing and grinding following turning

A newly designed finishing process utilizing an effective electrode and a grinding tool to execute the continuous electrochemical finishing and grinding processes following turning is described in this paper. The proposed process can be used for a variety of turning operations. Electrochemical finishing and grinding can be performed following the finishing process on the same machine by using a simple attachment. The factors affecting electrochemical finishing, grinding performance, and electrochemical finishing are discussed. The electrode was tested with both continuous and pulsed direct current. A higher work piece rotational speed produced a better finish. Changing the electrode design from a semicircle to a wedge form with a small end radius caused the electrolytic products and heat to dissipate more rapidly and provided the best finishing. Pulsed direct current finishing was slightly better than using continuous direct current finishing. However, the use of pulsed current would increase machining time and cost.