Finite-difference methods for simulation models incorporating non-conservative forces

We discuss algorithms applicable to the numerical solution of second-order ordinary differential equations by finite-differences. We make particular reference to the solution of the dissipative particle dynamics fluid model, and present extensive results comparing one of the algorithms discussed with the standard method of solution. These results show the successful modeling of phase separation and surface tension in a binary immiscible fluid mixture.Comment: 27 pages RevTeX, 9 figures, J. Chem. Phys. (in press

Stages of interior design in graphic editors

In the article the specifics of constructing interiors in graphic editors within the framework of design training with the most common errorsВ статье рассмотрена специфика построения интерьеров в графических редакторах в рамках обучения дизайну с указанием наиболее часто встречающихся ошибо

Magnetotransport in Double Quantum Well with Inverted Energy Spectrum: HgTe/CdHgTe

We present the first experimental study of the double-quantum-well (DQW) system made of 2D layers with inverted energy band spectrum: HgTe. The magnetotransport reveals a considerably larger overlap of the conduction and valence subbands than in known HgTe single quantum wells (QW), which may be regulated by an applied gate voltage $V_g$. This large overlap manifests itself in a much higher critical field $B_c$ separating the range above it where the quantum peculiarities shift linearly with $V_g$ and the range below with a complicated behavior. In the latter case the $N$-shaped and double-$N$-shaped structures in the Hall magnetoresistance $\rho_{xy}(B)$ are observed with their scale in field pronouncedly enlarged as compared to the pictures observed in an analogous single QW. The coexisting electrons and holes were found in the whole investigated range of positive and negative $V_g$ as revealed from fits to the low-field $N$-shaped $\rho_{xy}(B)$ and from the Fourier analysis of oscillations in $\rho_{xx}(B)$. A peculiar feature here is that the found electron density $n$ remains almost constant in the whole range of investigated $V_g$ while the hole density $p$ drops down from the value a factor of 6 larger than $n$ at extreme negative $V_g$ to almost zero at extreme positive $V_g$ passing through the charge neutrality point. We show that this difference between $n$ and $p$ stems from an order of magnitude larger density of states for holes in the lateral valence band maxima than for electrons in the conduction band minimum. We interpret the observed reentrant sign-alternating $\rho_{xy}(B)$ between electronic and hole conductivities and its zero resistivity state in the quantum Hall range of fields on the basis of a calculated picture of magnetic levels in a DQW.Comment: 15 pages, 13 figure

Diabetic ketoacidosis with mild hyperglycemia associated with the use of canagliflozin. Report of one case with type 1 diabetes

Indexación: Web of Science; Scopus; Scielo.Diabetic ketoacidosis with mild hyperglycemia is a major complication of sodium-glucose cotransporter 2 inhibitors. Although its use is not approved for patients with type 1 diabetes mellitus, the drug is often prescribed with the hope of optimizing metabolic control. We report a 20 years old female with hypo-thyroidism and type 1 diabetes consulting for vomiting and abdominal pain. The patient had used canagliflozin during the two previous months. Laboratory showed a blood glucose of 200 mg/dl, a severe metabolic acidosis (pH 7.1) and ketonemia. The patient was successfully treated in the intensive care unit.http://ref.scielo.org/65brd

Analysis of static characteristics of digital actuators of returning-forward movement

Проаналізовані різноманітні конструкції багатопозиційних приводів з цифровим керуванням, позиціювання яких здійснюється по жорсткому механічному упору. Обгрунтована доцільність застосування однотипних електропневматичних приводів поворотно-поступального руху в якості виконавчих пристроїв повороту і поступального переміщення вихідної ланки як приводів руки, так і приводів колони промислових роботів. Розглянуті оригінальні комбіновані багатопозиційні приводи поворотно-поступального руху з цифровим керуванням, які забезпечують як послідовні, так і одночасні поворот і лінійне переміщення вихідної ланки на задану величину. Запропонована математична модель розрахунку основних параметрів приводів повороту і приводів лінійного переміщення вихідної ланки. Приведений аналіз залежності крутного моменту і лінійного зусилля електропневматичного цифрового привода поворотно-поступального руху від розрядності пневматичного цифрового двигуна.Purpose. The goal of this work is to develop and research the multiposition rotary-progressive actuator with digital control. Design/methodology/approach. In industrial robots with two or more degrees of mobility mainly autonomous linear displacement actuators and angular rotation actuators are used. When using such drives, a challenge of combining constructive and kinematic functionality emerges. Solving this problem results in an increase of the overall size and complexity of the kinematic joint connection between the two drives. Various schemes of multiposition drives with digital and unitary control codes, for both progressive and the rotational motion to the output link have been considered. Proposed is an original digital electro-pneumatic rotary-progressive actuator, which is fairly compact and has a simple kinematic connection between its links. A mathematical calculation model for basic parameters of the drive has been developed, and the dependence of torque and direct force of digital electro-pneumatic rotary-progressive actuator on the number of digits of the pneumatic digital actuator has been analysed. Findings. Research has shown that the use of the proposed combined multiposition rotary-progressive drive with digital control considerably simplifies the construction and upgrades the functionality of industrial robots. Originality/value. The results of the research may be useful for specialists who develop and operate multi-position rotary-progressive actuators with digital control.Проанализированы различные конструкции многопозиционных приводов с цифровым управлением, позиционирование которых совершается по жёсткому механическому упору. Обоснована целесообразность применения однотипных электропневматических приводов поворотно-поступательного движения в качестве исполнительных устройств поворота и поступательного перемещения выходного звена как приводов руки, так и приводов колонны промышленных роботов. Рассмотрены оригинальные комбинированные многопозиционные приводы поворотно-поступательного движения с цифровым управлением, которые обеспечивают как последовательные, так и одновременные поворот и линейное перемещение выходного звена на заданную величину. Предложена математическая модель расчёта основных параметров приводов поворота и приводов линейного перемещения выходного звена. Приведён анализ зависимости крутящего момента и линейного усилия электропневматического цифрового привода поворотно-поступательного движения от разрядности пневматического цифрового двигателя

Improve the static and dynamic characteristics of pneumoelectric multipositional digital control drives

Стаття присвячена актуальній технічній проблемі – розробці та дослідженню пневмоелектричних і пневмогідравлічних багатопозиційних приводів з цифровим керуванням. Розглянута конструкція пневмоелектричного цифрового привода, в структуру якого входять пневматичний цифровий двигун, електричний кроковий двигун, пристрої регулювання швидкості руху вихідного штока, гальмування розрядних поршнів і компенсації зусилля на гвинтову пару. Запропонована математична модель для розрахунку основних характеристик пневмоелектричного цифрового привода з гідравлічним способом регулювання швидкості руху вихідного штока.Purpose. The goal of this work is to research and development the pneumoelectric multipositional digital control drives. Design/methodology/approach. At development of digital pneumatic actuators with small increment and enormity of moving of output rod it is necessary to take into account that with the increase of number of pistons static thrust is decreases and the axial overall size of pneumatic cylinder is increases. Decrease of static thrust is stipulated by losses on a friction, what proportional to the number of pistons and amount of seal on a piston. For equalizing of losses on a friction it is necessary to increase the diameter of pistons, that stipulates both the increase of overall sizes and metal consumption and air consumption during work of actuator. Proposed is an original pneumoelectric digital drive, that includes for itself a pneumatic digital engine, low-powered stepper motor, devices of braking of pistons and rate control of movement of output rod. A mathematical calculation model for the calculation of basic characteristics of pneumoelectric digital drive with the hydraulic method of rate control of movement of output rod. Findings. Research has shown that the use of the proposed multiposition pneumoelectric digital drive allows to improve him static and dynamic characteristics. It extends functional possibilities of such actuators considerably. Originality/value. The results of the research may be useful for specialists who engage in the design (to the calculation) of dynamic descriptions of multiposition actuators with digital control.Статья посвящена актуальной технической проблеме – разработке и исследованию пневмоэлектрических многопозиционных приводов с цифровым управлением. Рассмотрена конструкция пневмоэлектрического цифрового привода, в структуру которого входят пневматический цифровой двигатель, электрический шаговый двигатель, устройства регулирования скорости движения выходного штока, торможения разрядных поршней и компенсации усилия на винтовую пару. Предложена математическая модель для расчёта основных характеристик пневмоэлектрического цифрового привода с гидравлическим способом регулирования скорости движения выходного штока

Quasi-ballistic transport in HgTe quantum-well nanostructures

The transport properties of micrometer scale structures fabricated from high-mobility HgTe quantum-wells have been investigated. A special photoresist and Ti masks were used, which allow for the fabrication of devices with characteristic dimensions down to 0.45 $\mu$m. Evidence that the transport properties are dominated by ballistic effects in these structures is presented. Monte Carlo simulations of semi-classical electron trajectories show good agreement with the experiment.Comment: 3 pages, 3 figures; minor revisions: replaced "inelastic mean free path" with "transport mean free path"; corrected typing errors; restructered most paragraphs for easier reading; accepted for publication in AP

The peculiarities of ultrasound wave propagation in magnetorheological fluid with complex dispersive phase

This work is devoted to experimental study of the peculiarities of ultrasound wave propagation in magnetorheological fluid (MRF) with complex disperse phase under evaluation of changing of ultrasonic waves (UW) velocity in MRF on the base of water, oxide powder and carbonyl iron particles vs. intensity of applied magnetic field have been obtained. It was found that in the result of magnetic field separation the oxide layer thickness of MRF is increasing with the field value and can be determined by 2-3 µm and lesser

Surface state charge dynamics of a high-mobility three dimensional topological insulator

We present a magneto-optical study of the three-dimensional topological insulator, strained HgTe using a technique which capitalizes on advantages of time-domain spectroscopy to amplify the signal from the surface states. This measurement delivers valuable and precise information regarding the surface state dispersion within <1 meV of the Fermi level. The technique is highly suitable for the pursuit of the topological magnetoelectric effect and axion electrodynamics.Comment: Published version, online Sept 23, 201