Complementary variational finite-element solution of Eddy current problems using the field variables

A variational finite element method, based upon a functional related to the classical Lagrange density and originally embodied into a program intended for high frequency problems with loss, has been tested on a simple skin-effect eddy current problem. Either of the dual variables E or H may be used subject to complementary boundary constraints. The results so far have been worked in terms of the H variable and show good agreement with the theoretical skin-effect result.     

The synovial joint as an “intelligent” friction unit

A concept is advanced and a structural diagram is shown of the synovial joint as an “intelligent” friction unit possessing the properties of a cybernetic system. The joint demonstrates a record-low friction coefficient and compensation of cartilage wear as a triboengineering material maintaining human locomotor activity for many years. It is provided with a feedback system with the sympathetic center controlling the lubricating conditions of the movable joint of the articular bone ends, the lubricating fluid composition, and the elimination of debris from the articular capsule. The main reason why the joint fails is insufficient lubrication due to disruption of the exchange between the bloodstream and the joint synovial shell inducing a deficit of the lubricating synovial fluid. The disruption of the exchange is compensated by injecting synovial fluid substitutes. The paper shows the results of tribological studies and clinical trials providing evidence that the patient’s blood serum can be used as an absolutely compatible lubricating fluid to restore the functions of the articular synovial medium.     

Stripe delay filters

There are considered constructions of microsized stripe delay filters, which are realized on a basis of ceramic materials with high dielectric permittivity. Delay time of non-minimal phase filters is 7–12 ns at frequencies of 1900 MHz with relative bandwidth of 3.6–3.85%. Filters dimensions are comparable with ones used in portable communication devices. Dimensions of researched three-resonator filter at frequency of 1900 MHz are 8.4×5×2mmwith material dielectric permittivity ε_r = 92, and 5-resonator filter ones are 9.2×8.6×2 mm. Filters are different from traditional delay filters. Two filters of considered ones contain odd resonator number and the third one contains four resonators and it has two cross couplings. The basis of the filters is amount of step-impedance stripe resonators pairs located close to each others whose electromagnetic coupling behavior is capacitive. There are represented the results of frequency characteristics simulation for different delay filters.     

Thermal Blending Time Associated With a Charge of Hot Particles Added to a Fluidized Bed of Uniform Temperature

The process of heat transfer between particles in a fluidized bed is important for many industrial fluidized bed processes. The problem associated with studying this phenomenon is the confounding effect of particle mixing on heat transfer. The work described here was undertaken to describe the process in which heat is added to a fluid bed process by adding a hot charge of particles to a colder fluidized bed. The rate of heat transfer in this instance can have a significant impact on performance of the fluid bed process, depending upon its application. Both the method of analysis and the results of the work are applicable to other fluidized bed processes, particularly those associated with the thermal upgrading of heavy oil. The method of data analysis, based on binomial statistics, allowed useful data to be extracted from a complex system without the need for a large number of experiments. The analysis also allowed for some assessment of the relative importance of mixing and heat transfer, which has not been possible with other approaches. The results of the experiments were further explored using a bubbling bed model that incorporated both heat transfer and solids mixing. This allowed for the formation of a conceptual model, validated by the experimentation, that explains the relative functions of the two transfer processes in the dispersion of heat from a hot charge of particles to the bulk of a fluidized bed.     

Structurization of Steel Produced from Iron Doped with a Nanosized Silicon Carbide Composite Powder

Powder Metallurgy and Metal Ceramics - The features peculiar to the production of iron-based metal composites with additions of superfine composite powders synthesized as master alloys were...     

Structurization of Reaction-Sintered Silicon Carbide Modified by Chromium Carbide

Powder Metallurgy and Metal Ceramics - The structurization and phase composition of reaction-sintered silicon carbide (RSSC) modified by chromium carbide are examined. When hexagonal silicon...     

Role of PD-L1 in Gut Mucosa Tolerance and Chronic Inflammation

The gastrointestinal (GI) mucosa is among the most complex systems in the body. It has a diverse commensal microbiome challenged continuously by food and microbial components while delivering essential nutrients and defending against pathogens. For these reasons, regulatory cells and receptors are likely to play a central role in maintaining the gut mucosal homeostasis. Recent lessons from cancer immunotherapy point out the critical role of the B7 negative co-stimulator PD-L1 in mucosal homeostasis. In this review, we summarize the current knowledge supporting the critical role of PD-L1 in gastrointestinal mucosal tolerance and how abnormalities in its expression and signaling contribute to gut inflammation and cancers. Abnormal expression of PD-L1 and/or the PD-1/PD-L1 signaling pathways have been observed in the pathology of the GI tract. We also discuss the current gap in our knowledge with regards to PD-L1 signaling in the GI tract under homeostasis and pathology. Finally, we summarize the current understanding of how this pathway is currently targeted to develop novel therapeutic approaches.     

Blast-furnace operation with pulverized-coal injection and with chunk anthracite

In order to replace expensive coke, various fuels are added to the blast sent to the blast furnace: pulverized coal, natural gas, coke-oven gas, fuel oil, etc. A less common alternative is to introduce chunk anthracite through the charge hole. The use of chunk anthracite may considerably reduce the coke consumption and the production costs of the hot metal in circumstances where pulverized-coal injection is not employed and its introduction would require the use of high-quality iron ore and coke and also special preparations of the furnace and the associated systems. Chunk anthracite proves especially effective where there are constraints on the furnace productivity on account of production problems, the furnace is switched to slower operation, and plant economics must be improved.     

Structure and Properties of Ceramics Based on Monetite and Nanodispersed Silica

Powder Metallurgy and Metal Ceramics - Calcium–phosphate ceramics based on monetite and nanosized silica are produced by sintering at 500°C. It is established that phase changes and...     

Thin stripline bandpass filters for the centimeter band

This article considers the design of thin stripline (1 mm) bandpass filters in the centimeter band, which contain dielectrics with different relative permittivity ε _r . This includes the choice of the resonators, the dielectric material, the preliminary assessment of resonators’ unloaded quality factors and taking into account the features of the frequency response curve of the filter. It was found, that the passband width of the thin comb filters with λ/4 resonators and array-type filters with λ/2 resonators cannot exceed 6% for any values of ε _r and the length of resonators of at least 2 mm. The array-type filters with resonators of half-wave type and with alternating signs of the coupling factors between resonators were proposed. Under certain additional conditions, the attenuation poles appear in such filters, resulting in improved selectivity. The results of computer modelling of the frequency response curve of thin filters of cm band are presented. They are compared to the frequency response of other filters. The data obtained from computer modelling showed good correspondence with the experimental data.