Conical Base Research Articles

Laparoscopic Appendectomy with Immersive Appendiceal Stump Closure in Patient with Vermiform Appendix Abnormality

Background. Acute appendicitis is a common emergency surgical pathology, with laparoscopic appendectomy being the “gold standard” in its treatment.Aim. We report a clinical case of laparoscopic appendectomy with immersive appendiceal stump closure in a patient with vermiform appendix abnormality.Materials and methods. Patient K. was emergently admitted to the Surgical Hospital of Ekaterininskaya Clinic in June 2019 with a clinical picture of acute appendicitis. Symptoms, disease anamnesis, instrumental and laboratory examinations conformed to acute appendicitis.Results and discussion. The patient was rendered an emergent surgery. Intraoperative picture corresponded to acute phlegmonous appendicitis with malformation (a wide conical base) of the vermiform appendix. Immersive appendiceal stump closure was chosen as treatment. Alternative opinions coexist on justifying a particular appendiceal stump closure strategy. Immersive treatment is our method of choice in terms of implementation and safety in the particular clinical case. Th is method requires the surgeon’s technical experience.Conclusion. A clinical case is reported of performing laparoscopic appendectomy with immersive appendiceal stump closure in a patient with vermiform appendix malformation. Despite the appendix abnormality, immersive treatment of the appendiceal stump was justified as safe in this case and entailed no complications in postoperative period.

Новые исследования городища раннего неолита Каюково-2 на севере Западной Сибири

Purpose. The article presents results of new research at one of the most prominent Early Neolithic enclosed settlements in the North of Western Siberia – the stronghold of Kayukovo-2, which is characterized by a regular architectural plan with one central and five surrounding buildings, pottery of a specific shape and type, including flat as well as conical bases and complex ornamentation, and an original complex of stone artefacts. Results. In 2018, the investigation of building structure no. 4 was continued; for the reconstruction of the paleo-landscape, soil samples were investigated in the adjacent peatland, new radiocarbon dates were obtained, and analyses of the material complex represented by fragments of ceramics, products from clay-like raw materials and clay, stone artefacts, and clusters of small bone fragments was carried out. Building no. 4 was identified as a semi-sunken dwelling structure with a hearth in the centre, a small connecting corridor to building no. 7, and a link to the large central building no. 6. In 2019, new trenches confirmed the existence of a ditch circumscribing the settlement complex. Palaeoenvironmental research shows that during the period of use of the site, the closest water body was located c. 100 m from the terrace shore. The radiocarbon dates available up to now indicate a time of functioning of the ancient settlement in the first centuries of the 6th millennium cal BC. The ceramic material belongs to the complex of early flat-based hunter-gatherer pottery of Western Siberia, a tradition which probably spread from the Baraba forest-steppe and the Ishim region to the Northern Trans-Urals around 6000 cal BC. Conclusion. The reasons for the emergence of the northernmost fortified settlements in Eurasia among hunter-gatherer communities with complex architecture and specific ceramics, the role of internal socio-cultural mechanisms and external influences, and environmental factors in their formation continue to be under discussion and require further research.

Development of a novel high-temperature, pressurised, indirectly-irradiated cavity receiver

The concentrated solar thermal industry is moving towards higher temperature receivers. Gas-phase receivers represent a near-term solution that can achieve such temperatures, but most designs for pressurised receivers require a window. The window represents the weak link in the designs, limiting a receiver’s operational life, temperature, and pressure. Indirectly-irradiated receivers, which do not require a window resolve these issues, but introduce a detrimental performance trade-off because solar energy must be effectively conveyed through a solid receiver wall. This can result in a lower thermodynamic efficiency (first and second law) since there is a large difference in temperature between the inside and outside of the receiver wall. To deal with these issues, this paper investigates novel, indirectly-irradiated receiver designs with the potential to reduce the temperature drop across the receiver wall. The proposed new type of cavity absorber was designed by first considering its optical performance via a detailed ray-tracing analysis. These results indicated that a cylindrical cavity with an inverted conical base provides the highest optical efficiency, around 92%, compared to other cylindrical cavities with different base shapes. Next, to reduce the temperature drop in the design, heat transfer enhancements for the cavity wall were explored using the ray tracing-calculated radiative flux. It was found that a compound technique of impinging jets on an extended surface enables more design freedom while also providing higher convective heat transfer coefficients compared to either technique alone. To explore the range of heat transfer enhancements that are possible with these methods, this paper also presents parametric performance maps of heat transfer coefficients and pressure drop as a function of nozzle-to-cavity distances, nozzle diameters, and the number of nozzles. According to this analysis, a design with around 48 nozzles per square metre, each of 9 mm diameter, around a metal foam-covered cavity, achieved the optimum design point with respect to the overall heat transfer efficiency. Overall, it was found that an optimally designed indirectly-irradiated gas-phase receiver can indeed provide high performance and can potentially enable solar systems to reliably operate at well above 600 °C for driving advanced thermodynamic cycles.

CFD–DEM simulation of fine particles in a spouted bed apparatus with a Wurster tube

In this work, a coupled computational fluid dynamics–discrete element method (CFD–DEM) approach was employed to evaluate the spouting behavior of fine, cohesive powders in a cylindrical spouted bed with a conical base and equipped with a Wurster tube. The particle and gas dynamics inside the apparatus were simulated with 1.7 million spherical ZrO2 particles with a particle size of 100μm. For an accurate prediction of the interactions of cohesive particles in the spouted bed, the adhesion forces according to JKR theory were included in the Hertz–Tsuji contact model. The surface energy of the particles was varied over a wide range to determine the effect of the adhesion on the spouting (the fountain shape and maximum height as well as the distribution of the concentrations and velocities of particles in different zones of the apparatus). A detailed analysis of the collision dynamics was conducted. The spouting behavior of a spouted bed with the same dimensions, particles, and processing parameters was recorded with a high-speed camera. The CFD–DEM simulations showed good agreement with the experimentally captured spouting behavior.

Drying of pasty and granular materials in mechanically and conventional spouted beds

A contactor vessel was built to operate as either a mechanically or a conventional spouted bed for the purpose of analyzing the drying of pasty and granular materials under comparable conditions in both configurations. A classical conical–cylindrical spouted bed with a 60° conical base and an air inlet central orifice was modified to enable the switch by introducing in the vessel’s center an open helicoidal conveyor screw placed above the air inlet orifice. This screw is removable and conveniently returns the bed to its conventional spouted configuration. Experiments on drying solutions (calcium carbonate suspensions and skimmed milk) and granular materials (porous alumina particles) were performed for various bed parameter settings. The spouting pressure drop, outlet air temperature, and relative humidity were measured over time under different conditions. Mechanical agitation is proved effective in drying diluted carbonate calcium liquid suspensions and coarse porous alumina particles at an air velocity approximately 50% lower in comparison to drying in a conventional spouted bed. The conventional spouted bed performed better at drying liquid skimmed milk as the mechanical agitation combined with the axial inlet air flow is not effective in mitigating sticking and powder agglomeration in the bed when handling pastes of complex composition. Introducing mechanical agitation in the designed setup broadens the operating range of a conventional spouted bed with axial air flow in the inlet.

Study of Pressure Drop in the 2D Spouted Bed with Conical Base of Binary Particle Mixtures: Effects of Particle Size and Density

In this study, the pressure drop for the binary mixtures of particles differing in size and density in a pseudo-2D spouted bed was experimentally studied. A binary mixture of solid particles including sand, Gypsum, and polyurethane was used in the experimental setup. Effects of static bed height, cone angle, particles diameter, and a particles weight fraction on the bed pressure drop were evaluated. The relationship between the peak pressure drops of the binary mixtures to the minimum spouting velocity was discussed. The trend of variation of pressure drop versus superficial gas velocities for binary particle mixtures in the spouted beds was found to be similar with that for the single sized particle system. The particles that sink to the bed bottom are called jetsam, whereas those gathered at the upper section of the bed are called flotsam. At the same air velocity for jetsam and flotsam rich systems, the maximum pressure drop in the jetsam rich system was larger than the flotsam one. The measured values of minimum spouting velocity were compared with some empirical correlations for single sized particles in spouted beds.

The tunneling potential for field emission from nanotips

In the quasi-planar approximation of field emission, the potential energy due to an external electrostatic field E0 is expressed as −eγE0Δs, where Δs is the perpendicular distance from the emission site and γ is the local field enhancement factor on the surface of the emitter. We show that for curved emitter tips, the current density can be accurately computed if terms involving (Δs/R2)2 and (Δs/R2)3 are incorporated in the potential where R2 is the second (smaller) principle radius of curvature. The result is established analytically for the hemiellipsoid and hyperboloid emitters, and it is found that for sharply curved emitters, the expansion coefficients are equal and coincide with that of a sphere. The expansion seems to be applicable to generic emitters as demonstrated numerically for an emitter with a conical base and quadratic tip. The correction terms in the potential are adequate for Ra⪆2 nm for local field strengths of 5 V/nm or higher. The result can also be used for nano-tipped emitter arrays or even a randomly placed bunch of sharp emitters.

Thermal Buckling of Thin Conical Shell Subjected to Uniform Pressure and Temperature

The thermal buckling of the shell is one of the hot research fields in the field of solid mechanics. In this paper, the equation of thermal constitutive equation of isotropic material and the stability of axisymmetric conical shells were derived by tensor method. Application of thermal constitutive equation to the study of thermal buckling of conical shells, the equations of thermal stability of conical shells expressed by displacements were obtained. Considering the interaction of uniform external pressure and temperature, potential energy functional of conical shells is derived by the principle of minimum potential energy expressed in displacement, the thermal buckling of simply supported cone shell using Ritz method. The change trend of critical pressure and critical temperature caused by the change of conical shells wall thickness and base angle analysis.

Stability and performance of a spouted bed in drying skimmed milk: Influence of the cone angle and air inlet device

ABSTRACTThis paper investigates the skimmed milk drying over inert particles in a 30 cm diameter spouted bed. Drying was evaluated for conical bases of three cone angles (45°, 60°, and 75°) operating with 4.5 kg of inert particles, and two air inlet devices with different geometries—a Venturi-type nozzle and a straight section pipe. The drying capacity was evaluated from the maximum paste feed rate that allowed stable operation and spouting dynamic behavior throughout drying. It was observed that drying capacity and dynamic stability were greatly affected by the cone angle and the inlet device geometry. From the conditions evaluated, the best configuration with regard to the drying capacity was obtained for the 45° conical base using the Venturi-type inlet device. In this dryer, a rate of 40 mL/min of skimmed milk was processed and a powder with a moisture content of about 10% was produced. The good performance on this configuration was attributed to several factors that affected positively the solid circulation rates and the dynamics stability. Such factors include the operation under a higher static-bed height, the spouting on conical configuration, and the improved aeration of the annular region provided by the inlet device. At this configuration, and for paste feed rates up to the maximum admissible value, the spouted-bed dynamic was almost not affected by the liquid and the wet bed operated under dynamic conditions very similar to those of the dry bed. Using a 75° conical base with the Venturi-type inlet device under a slightly lower drying capacity (35 mL/min) also resulted in quite stable dynamic conditions. The 60° conical base with the Venturi-type device was the configuration that performed worst with regard to drying capacity (30 mL/min).

Measurement on soil deformation caused by expanded-base pile in transparent soil using particle image velocimetry (PIV)

A new small-scale geotechnical physical model in 1-g and unconfined condition, combining the transparent soil, close-range photogrammetry and particle image velocimetry (PIV), was employed, which provides a non-intrusively internal deformation measurement approach to monitor the internal deformation of soil caused by expanded-base pile jacking with casing. The transparent soil was made of fused quartz and its refractive index matched blended oil, adding reflective particles (glass beads). Close-range photogrammetry was employed to record the images of the process of casing jacking and extraction in transparent soil, allowing the use of Matlab-based Geo-PIV to figure out the displacement field converted from image space to object space. Analysis of test results indicates that the maximum displacement caused by casing jacking for expanded-conical-base pile is decreased by 29% compared with that for expanded-flat-base pile. The main movement happens at the early stage of casing extraction. The maximum displacement caused by casing extraction for the conical base is about 43% of that for the flat base, while the affected zone caused by casing extraction for the conical base accounts for about 1/3 of that for the flat base. The contraction for horizontal displacements tends to decrease with the depth increasing. By contrast, the contraction under pile base decreases with the increasing of displacement. The displacements generated by jacking a conventional pile having a diameter equal to the casing diameter of the expanded-base pile were comparable to the net displacement taking place due to expanded-base pile installation for the conical base pile.

Comparative Study Between Peristomal Patches in Patients with Definitive Tracheostomy.

Introduction To prevent or diminish pulmonary problems in laryngectomized patients, continuous use of a heat and moisture exchanger (HME) is recommended. Therefore, automatic speaking valves are also often combined with an HME to enable hands-free speech. In order to keep these devices in place, most commonly, peristomal patches are used. Objective This prospective clinical 2 × 2 crossover study aims at assessing the added value of a new patch for HME application, the Provox StabiliBase OptiDerm (SBO). The device combines the stable and conical base of the Provox StabiliBase with the skin-friendlier hydrocolloid Provox OptiDerm (OD) patch. Methods Thirty-two laryngectomized patients were included in this multicenter study. Participants were asked to compare SBO to OD, and to the patch they normally use. The primary outcome measure was patient preference. Results Overall, 60% of the participants had preference for their normally used patch, 23% preferred the SBO and 17% indicated no preference. When comparing the SBO to the OD, 43% preferred the SBO, 40% the OD and 17% had no preference. Conclusion Most patients preferred their normally used patch and SBO was favored by a subgroup. Provox StabiliBase OptiDerm seems to be a valuable addition to the existing patches and further increases patients' options for HME application.

Calculation of Effective Emissivity of Isothermal Diffuse Cylindrical-inner-cone Cavity using Polynomial Interpolation Technique

A precise calculation of the effective emissivity of isothermal diffuse cylindrical-inner-cone cavities is presented using the polynomial interpolation technique. Particularly, results are obtained for the effective emissivity of conical bases of the isothermal diffuse cylindrical-inner-cone cavities. Comparisons are made between Chu Zaixiang's and our results for various values of the axial length, the radius of aperture in the lid and the half-angle of the inner cone. These demonstrate considerable simplicity and high accuracy of the calculating technique can be achieved, especially for the cavities of high intrinsic emissivity of the wall, long cylinder length, and small aperture radius. For application, a series of explicit analytical expressions in the polynomial forms are also presented.

EFFECT OF ATOMIZER INTERNAL GEOMETRY ON THE INTERNAL AND EXTERNAL TWO-PHASE FLOW IN EFFERVESCENT ATOMIZATION

An experimental study was conducted to study the internal and external two-phase flow in an effervescent atomizer using high-speed imaging. The impact of the aerator tube configuration and mixing zone length on the size of bubbles inside the mixing zone and the spray droplet characteristics at different gas-to-liquid flow rates ratios were studied. An aerator tube with the conical end base was manufactured and tested. It is observed that the separation bubble at the trailing edge is suppressed by this configuration, which resulted in more uniform and smaller bubbles compared to the standard aerator tube with a flat base. The length of the mixing zone was found to have an impact on the bubble size distribution inside the mixing zone; more uniform and smaller bubbles are generated in the shorter mixing zone. The mixing zone length, however, does not show a distinct impact on the droplet velocity and size. It is concluded that a conical base aerator tube and a shorter mixing zone could significantly improve the spray steadiness and the atomization process.

Figurilla femenina embarazada con símbolo astral en la antigua Caura: ¿súplica privada a Dea Caelestis?

Estudiamos en este artículo una pequeña terracota procedente de la antigua ciudad de Caura, hoy Coria del Río (provincia de Sevilla). Aunque no se conserva completa, representa una figura femenina en estado de gestación. La imagen se apoya sobre una base troncocónica hueca que exhibe en su parte delantera un símbolo astral. Es posible que dispusiera inicialmente de brazos abiertos en actitud orante. Estos rasgos sugieren interpretar la figurilla como ofrenda o exvoto (¿a Dea Caelestis?), y en cualquier caso como producto de un acto piadoso para propiciar la maternidad. La pieza puede fecharse, sin mayor precisión de momento, en época romana. La dispersión del tipo refleja un importante arraigo en zonas con un marcado sustrato púnico.

Magneto-absorption in conical quantum dot ensemble: Possible applications for QD LED

In the framework of the adiabatic approximation, the energy states of electron, as well as the direct light absorption are investigated in conical quantum dot under the external magnetic field. Analytical expressions for the particle wave function and energy spectrum are obtained. The dependence of the absorption edge on the geometrical parameters of conical quantum dot is obtained. Selection rules are revealed for transitions between levels with different quantum numbers. Absorption coefficient dependence on the frequency of the incident light is revealed taking into account dispersion of conical quantum dot's base radius for both cases of symmetric and asymmetric distribution functions. Such structures are very promising and can be used for the element base quantum dots LEDs.

Discriminative separable nonnegative matrix factorization by structured sparse regularization

Non-negative matrix factorization (NMF) is one of the most important models for learning compact representations of high-dimensional data. With the separability condition, separable NMF further enjoys a global optimal solution. However, separable NMF is unable to make use of data label information and thus unfavourable for supervised learning problems. In this paper, we propose discriminative separable NMF (DS-NMF), which extends separable NMF by encoding data label information into data representations. Assuming that each conical basis vector under the separability condition is only contributable to representing data from a few classes, DS-NMF exploits a structured sparse regularization to learning a sparse data representation and provides higher discrimination power than the standard separable NMF. Empirical evaluations on face recognition and scene classification problems confirm the effectiveness of DS-NMF and its superiority to separable NMF.

Enhancement of Uniformity of Solid Particles in Spouted Bed Using Stochastic Optimization

Performance of gas-solid spouted bed benefit from solids uniformity structure (UI).Therefore, the focus of this work is to maximize UI across the bed based on process variables. Hence, UI is to be considered as the objective of the optimization process .Three selected process variables are affecting the objective function. These decision variables are: gas velocity, particle density and particle diameter. Steady-state solids concentration measurements were carried out in a narrow 3-inch cylindrical spouted bed made of Plexiglas that used 60° conical shape base. Radial concentration of particles (glass and steel beads) at various bed heights and different flow patterns were measured using sophisticated optical probes. Stochastic Genetic Algorithm (GA) has been found better than deterministic search for study mutation of process variables of the non-linear bed. Spouted bed behaved as hybrid system. Global GA could provide confirmed data and selected best operating conditions. Optimization technique would guide the experimental work and reduce the risk and cost of operation. Optimum results could improve operating of the bed at high-performance and stable conditions. Maximum uniformity has been found at high-density, small size of solid beads and low gas velocity. Density of solids has been effective variable on UI.Velocity of gas and diameter of solid particles has been observed more sensitive decision variables with UI mutations. Uniformity of solid particles would enhance hydrodynamic parameters, heat and mass transfer in the bed because of improving of hold-up and voids distributions of solids. The results of the optimization have been compared with the experimental data using sophisticated optical probe and Computed Tomography technique.

Orbiting Next-Gen Technology: The Women Behind Boeing's MexSat Satellite [Amperes: Current Affairs from Around the World

In July 1963, Syncom, the world's first geosynchronous communications satellite, launched from Cape Canaveral, Florida. It was a month before Martin Luther King, Jr.'s march on Washington, D.C. Twenty-six-year-old Russian Valentina Tereshkova had just become the first woman to travel in space. The satellite, looking something like a table lamp with its conical base and shimmering shade, was used in the first live two-way satellite call between heads of government when U.S. President John F. Kennedy telephoned Nigerian Prime Minister Abubakar Balewa.

Hydrodynamic study of a multiphase spouted column

The capability of Euler multiphase averaged transport model to predict hydrodynamic characteristics (pressure drop, gas holdup and solid concentration) of a multiphase spouted column is analyzed using computational fluid dynamic (CFD). The Navier–Stokes equation is solved with ANSYS CFX built-in closures: two equations turbulence (k–ε a, k–ω, SST), and semi-empirical correlations for interphase forces (drag, turbulent dispersion and lift forces, virtual force). To ensure the reliability of the CFD simulations, the models are validated against experimental data for the two phase air–water and the three phase air–water–sand system in a spouted column with a draft tube and a conical base at 25°C and 1atm and varying superficial air velocity (0.572m/s, 0.00.0944m/s, 0.1605m/s, 0.2172cm/s) [22]. Steady state conditions capture the flow conditions for the two-phase (air–water) system while transient conditions is need the for three-phase simulations (air–water–sand). The mixing regions and the moment exchange is correctly characterized by a free-wall turbulence using k–ε and k–ω two equations turbulence closure models for the two phase dispersed air–water system [30,32], while the SST turbulence model instead of k–ε model is needed to improve predictions of solid concentrations close to internal walls for the dispersed air–water–sand system. The drag is the most significant coupling force, for the two and three phase system. Ishii–Zuber drag model is compared against and Grace adjusted drag model for air–water system, it predict the hold-up within 0.14% while Grace model within 0.44% requiring greater computational cost to tune the model empirical parameter [31,32], and the Schiller–Naumann drag coefficient is used for sand-water. For the two phases system best concordance between the simulated and experimental data are achieved for inlet gas velocity (u0) of 0.2172m/s (2% error in the predicted air hold-up). For the three phases system, in the concentric tube, and for an air superficial velocity of 0.2172m/s, the deviation in the estimated sand concentration is near 23% a while the error in the predicted air hold-up is within 2%. The observed deviation can be attributed to the chosen effective bubble size of the dispersed phase in the two phase system and the choice of drag force models and turbulence closure the three phase system.

Flow pattern and transition in gas–liquid–solid three phase spouted bed

The flow patterns and transitions in a gas–liquid–solid three phase spouted bed were investigated. Experiments were carried out in a cylindrical and a semi-cylindrical spouted bed with conical base. Glass beads and water were used as the solid phase and liquid phase, respectively. The changes in pressure drop and photographs were used to determine the flow patterns. Five distinct flow patterns were identified and described, i.e. fix bed (FB), grain spouting (GS), cluster spouting with slugging (CS-S), solid fixed with gas–liquid bubbling (SF-GLB), and slurry agitated bed (SA). Flow pattern maps of a three phase spouted bed (d=2.6mm, H0/Dt=1.86) under different liquid saturations were plotted. It was found that the flow pattern transition with the spouting gas velocity increasing at different liquid saturations (S) could be divided into three stages, i.e. transition from FB to GS when S<0.2, transition from FB to CS-S when 0.2<S<0.5, and transition from SF-GLB to SA when S>0.5. Increase in liquid saturation (S) always leads to increasing of the amplitude of pressure fluctuations. Besides, in stage I (GS), the minimum spouting velocity increases initially and then decreases apparently with increasing S. The range of stage I region becomes wider with lower initial bed height and particle diameter.