bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of dynamics of roll forming processes
Authors: Kondratenko Leonid A. , Mironova Lubov I.
Published: October 2018

This article contains the analysis of tube expander dynamics in complex interaction of structural elements of heat-exchange tubes attachment assembly in the process of roll-forming operation, description of dynamic process theoretical aspect. It is shown that torque variations lead to velocity fluctuations and influence the service life of operative parts of tube expander and quality of tube attachment assemblies.
For an incompressible lubricant in the bearing sliding surfaces of the spherical segments with the adjusted surfaces
Authors: Zavyalov Oleg
Published: October 2018

A mechanism consisting of a deformable surface and a gear unit with a curve is considered. An incompressible viscous liquid is applied to the surface. The gear unit rotates or moves along the surface. Under the influence of the load, the gear unit can deform the surface. Such a mechanism can be considered as a sliding bearing. Using the tensor analysis apparatus, it is proved that in all cases a thin layer of incompressible lubricant is formed. The results of the following studies are presented: The effect of the lubricant with harmonic oscillations of the gear unit is normal to the surface. With the harmonic oscillations of the gear unit, the velocity distribution of the liquid in a thin liquid layer depends only on the dimensionless amplitude of the oscillations. The incompressible fluid flows out beyond the edges of the gear unit when the thickness of the layer (the movement of the tooth to the surface) decreases between it and the surface and flows from outside with the increasing thickness (removing the tooth from the surface). The appearance of the bearing capacity of such a mechanism is associated with the forces of friction and inertia inside the fluid.
Mathematical modeling of making mechanical engineering products based on an information model
Authors: Govorkov Aleksey , Lavrenteva Mariya , Fokine Igor
Published: October 2018

The paper dwells upon computer-aided mechanical engineering. We herein propose a concept of choosing operations for producing a standard airframe part based on a product image and industrial environment object classifiers. Such industrial environment objects and their inter-relations are described as a set-theoretic model.
On the issue of formation the air noise component at workplaces of the diesel locomotives crews
Authors: Yaitskov Ivan
Published: October 2018

The article is devoted to the general acoustic system of the diesel locomotives which is a combination of the diverse noise and vibration sources creating the increased levels of the sound pressure in the workplaces of the machinists and locomotive crews. Factually, the sound field at the calculated points is created by the simultaneous action of the air and structural noise component sources. It is included the emitters to the sources of the air noise component which inboard the body structures and, accordingly, emit sound energy into the closed air volumes. And it is the sources which are set externally in particular the “wheel-rail” subsystems. It can be assumed that among the internal sources the maximum sound power is radiated by the power system namely by the internal combustion engines. For different types of the diesel locomotives, the setting of the internal combustion engines has significant differences to the work places of the locomotive crews. Therefore, this article considers four computational schemes for the diesel locomotive, obtains the analytical dependences of the sound pressure levels and reduces to the convenient form for engineering calculations at the design stage of the research objects. To reduce the noise source of the internal combustion engine while it is appearing in the conditions of the machine-building processes is almost impossible. Moreover, the main practical and technological feasible ways are to choose sound-absorbing materials and achieve sound insulation based on the existing sanitary noise standards.
Theoretical study of electrical contact dustiness impact on the transition resistance
Authors: Lyuminarskaja Ekaterina , Lyuminarsky Igor , Selivanov Kirill
Published: October 2018

The article considers a mathematical model for determination of transition resistance in electrical contacts. The suggested model considers elastic, elastoplastic and plastic deformations of micro-protrusions on rough contact surfaces, the presence of surface films and dust particles on them. A theoretical dependence of possible contact failure on dust content has been obtained.
Rationale construction of individual elements of technological complex
Authors: Nemtinov Kirill , Eruslanov Alexsey , Nemtinova Yulia
Published: October 2018

In this paper, we propose the substantiation procedure of a technological complex design on the example of a seeding complex. As a result of performed research, design of the seeding complex for grain crops has been improved using non-standard devices and typical parts that provide: reduction in the time of seeding and energy consumption, possibility of using the seeding complex as a cultivator and a disk harrow. Analysis of computational research results allowed us to specify the following parameters: disc angle of 15 degrees, while the specific traction resistance of the seeding complex does not exceed 3.44 kN/m on the stubble background, and 3.19 kN/m on the fallow background. Field studies of the developed complex has shown that at the given seeding depth (with the variation ± 1cm) the accuracy is 83.5 ... 84.2 %. Optimum quantity of plants of grain crops per unit area is provided under the following conditions: bucket volume 7,2 dm3, distance between buckets 0.21 m; speed of the bucket elevator is 0.12 m/s. The proposed design of the seeding complex is recommended to be used for combining several operations: soil preparation, sowing of cereals and soil packing.
Innovative development of Russian enterprises
Authors: Mechikova Maria , Kovaleva Nataliya , Vorontsova Olga
Published: October 2018

This study is devoted to the study of industrial innovation in Russia, the analysis of the main indicators of innovation activity, the identification of positive and negative trends in the development of domestic innovation, as well as methods of state support for innovation in Russia.
Usage of the device keeping the driver from falling asleep as a factor in reducing road accidents
Authors: Bogdanov Andrey , Popova Svetlana , Kalugin Anton , Ivanov Vitaliy
Published: October 2018

A significant proportion of internal transportation of goods is carried out by road. Statistics show that a large number of road traffic accidents, including fatalities, have to do with the driver falling asleep behind the wheel. A method was developed to stop the driver from falling asleep behind the wheel and a device to implement it; as a result, a patent for an invention was obtained. Some experimental studies were realized to implement this method and ensure the functioning of the device. As an example, the results of an experiment with KAMAZ 55102 motor vehicle were quoted, including the measure of the steering wheel angle (αBH = 4,6°) above which it is considered as steering of the wheel operator. In addition to that, the value of the minimum allowable number of steerings of the awake operator in a unit of time was given, and it came up to 0.5 steerings a second. Based on the experimental studies, some theoretical dependences describing the operation of the device preventing the driver from falling asleep at the wheel of a vehicle were developed.
The test bench of a cascade heatpump installation of a heat power complex for highly effective use secondary and renewables
Authors: Papin Vladimir , Bezuglov Roman , Veselovskaya Elena
Published: October 2018

In article the solution of one of the problems facing developers of a heat power complex for highly effective use secondary and renewables reveals. The solved problem is a development of the circuit decisions providing tests of all set of the modes of cascade heatpump installation of a heat power complex, design of the test bench. The developed complex allows to use most effectively together with heatpump installations and thermal accumulators renewables. Also the complex uses also household overflows of energy for the consumer’s heat supply, as much as possible reducing consumption of organic fuel.
Certification tests of a protective device such as ROPS to ensure safe usage of tractors
Authors: Troyanovskaya Irina , Kalugin Anton
Published: October 2018

According to the safety requirements, all protective devices of tractor units are subject to obligatory certification. One of the main means of protecting the operator during overturning is ROPS system. In accordance with GOST (National State Standard), a performance check of ROPS protective structures is carried out on basis of full-scale tests. The purpose of the presented study is to develop the experimental procedure and to obtain the performance check result of ROPS protective device of the tractor unit’s cabin using B10 bulldozer manufactured by the Chelyabinsk Tractor Plant as an example. The tests were carried out at the Ural Test Center NATI. For this purpose, a special bedplate was used, allowing to test the protective cabins of tractors with the total mass of up to 110 tons. The hydraulic system of the bedplate allowed to carry out the process of lateral loading of ROPS step by step, where each step corresponded to the 10 mm structure deformation. The applied load and structure deformation were recorded at each step. The energy accumulated by the structure was calculated as the area under the stress-strain curve. The energy U = 40867 J, which was required according to GOST, was accumulated during lateral deformation Δ = 270 mm. The force constituted Fy = 243 kN. After removing the lateral load, the structure was subjected to the vertical static and longitudinal loading. During the whole experiment of ROPS protective device, repairs, deformation corrections and adjustments were not allowed. The test results of ROPS structure of B10 bulldozer cabin showed compliance with the GOST safety requirements. During ROPS deformation, penetration of the protective structure elements into the driver’s limited zone was not observed.
Analysis of oscillations of a mechanical system with inertial exciters at an alternating position of it’s mass center
Authors: Eremeykin Sergey , Panovko Grigory , Shokhin Alexander
Published: October 2018

Numerical simulation results of dynamics of a mechanical system with self-synchronizing unbalance exciters with displaced center of mass relative to the initial centered state are described in application to analysis of dynamics of vibrating machines with variable position of operation load. Features of self-synchronization of exciters are revealed depending on position of the center of mass. Influence of position of the center of mass on resonance frequencies and modes is presented.
Development and research of the rotating lever object as a dynamic model of a cycle mechanism
Authors: Telegin Viktor , Kozlov Alexander , Shumilova Tatyana
Published: October 2018

The operation of high-speed automatic machine mechanisms causes oscillating (dynamic) processes because of the elastic deformation of their elements. This results in a sharp increase in loads in the mechanism links and a decrease in their positioning accuracy. The quantitative estimation of dynamic processes is performed on the basis of modeling the mechanisms by systems of concentrated masses connected by elastic-dissipative and kinematic bonds. One way to develop such systems and describe them mathematically is the method of representing the mechanism as a set of a limited number of objects, each of which represents either a typical mechanism or its separate part. This article considers the development and research of the mathematical model of the rotating lever as one of the most common elements of cycle mechanisms which also include cam-leverage, crank-and-rod and other mechanisms.
Reliability research of eccentric freewheel mechanisms of friction type
Authors: Sharkov Oleg , Koryagin Sergey , Velikanov Nikolay
Published: October 2018

The article contains a research of the influence of design parameters (material, the jamming angle) on operation reliability of eccentric friction-type freewheel mechanisms using calculated and experimental techniques. As the investigated factor, the lower limit of the confidence interval for the time between failures is adopted It is shown that the necessary reliability of the eccentric freewheel mechanisms is ensured when jamming angles are 8–10° and when their elements are made of material 100Cr6. The reliability of such mechanisms is 1.7 times higher than of roller free-wheel mechanisms. The results of the research can be used when predicting the reliability of the mechanisms in the drives of machines.
Establishment of production of special wheel and track technology for extreme natural-climate conditions of the Arctic
Authors: Diakov Alex S. , Kotiev George O.
Published: October 2018

The complex natural and climatic conditions of the Arctic Zone of the Russian Federation (AZ of the RF) make it necessary to put forward special requirements for all types of ground equipment used to solve transport problems in this region. At present, the increase in economic costs in the operation of machinery is primarily due to the mismatch of the design of the vehicles used in the climatic zone. A set of measures for land transport that allows to ensure the socio-economic development of the AZ RF.
Simulation modeling of the curvilinear motion of an industrial tractor with a differential rotation mechanism and tracking trajectory stabilization system
Authors: Kondakov Sergey V. , Dyakonov Aleksandr A. , Dubrovskiy Nikita V.
Published: October 2018

The article is devoted to the investigation of the transient processes in the hydrodynamic transmission and hydro-hydraulic turning mechanism at the entrance to the turn and turning on the spot. Boundary ground conditions are determined for the tractor to perform stepless maneuvering while performing technological operations. The algorithm of the tracking system has been formulated, which made it possible to keep the radius of the trajectory fixed by the handwheel as the external resistance to movement changes.
Analysis of methods of assessing the quality of protective paint car coatings
Authors: Avakov Arthur , Kosenko Evgeny , Topilin Ivan , Kopilov Fedor
Published: October 2018

At present, modern ways to protect a varnish coating of cars have become widespread among motorists. Small particles of dirt, dust, winter reagents, minuses of car wash systems, a large number of stones on the road do not have the best effect on car cover. All operational impacts destroy the protective paintwork, after which the steel car body is no longer able to resist the effects of the environment. The body begins to rust and deteriorate. The car eventually loses its appearance, ceases to shine, becomes opaque. Reduction of adverse operational impacts on the paint coating of the car is achieved by modern methods of protection. A wide distribution in the market of automobile cosmetics was produced by protective polishes based on wax or synthetic constituents. It is connected with their small cost and ease of application. The flagship on auto market for the protection of car paint coating is armor plate. This is a protective transparent film with a thickness of approximately 100 microns, providing the maximum degree of protection. Thus, with the help of modern means of protecting paint coating, one can minimize the negative impact of the environment and prolong youth to a car.
Digital technologies in questions of automated manufacturing management systems
Authors: Shutikov Michail , Ponomarev Kirill , Feofanov Alexander , Grishina Tat’jana
Published: October 2018

The article states that today in industry 4.0 are widely used automated and computerized control systems of industrial processes of the enterprise. It is stated that one of the types of such systems are MES-systems. The most popular MES-systems are presented, and it is revealed that the use of such systems in the service of the quality of the enterprise will improve the competitiveness of the enterprise. It is specified that the MES-system “FOBOS” is suitable for implementation in departments of quality service of the enterprise, the main advantages and opportunities of this MES-system are described. The article suggested that in order to exclude the possibility of unauthorized access to the MES-system, it is necessary to introduce an information security system. The main ways to ensure the security of data contained in the system are indicated. In conclusion, it is emphasized that the use of optimization and automation of the enterprise is an important step in the context of the transition to industry 4.0.
Endurance tests of single machines production
Authors: Kasyanov Valery , Deryushev Viktor , Shulkin Leonid , Kosenko Evgeny , Kotesova Anastasia
Published: October 2018

The paper proposes to consider the reliability of machines in terms of mass and individual production. The proposed approach makes it possible to assess the impact of various failures of machine parts on the reliability of single-purpose vehicles. Failures occurring as a result of fatigue wear are considered, but they are of a sudden nature of failure. A condition is defined to prevent such failures, from which the assigned resource to the limit state of the part must be less than the resource of each particular part that may be susceptible to sudden failure. This condition can be applied both for serial production machines and for single-source machines. An algorithm for determining sample and aggregate parameters and an algorithm for resource testing for reliability for single-source machines are proposed. The key stage for the development of the algorithm is the resource testing of machines, the carrying out of which makes it possible to objectively assess the reliability of the loaded parts. To reduce the period for obtaining test results, it is necessary to carry out accelerated resource tests of machines, which can be achieved by intensive operation of machines with short stops for inspection and maintenance. Failures resulting from tests constitute a sample that, after being processed by theoretical laws, allows the determination of the smallest values. Studies have shown that even with the estimation of sample values, the possibility of premature failure continues. In this regard, the paper proposes to use the aggregate parameters to estimate the minimum values. The use of such an algorithm will make it possible to exclude the possibility of the onset of premature failures by determining the period of operation of vehicles during which the failure-free operation of cars is guaranteed.
Efficiency of use of the solid-state YAG: Nd-Laser for hardening of high-strength cast iron VCH 70-3
Authors: Ivanov Maxim , Burlachenko Oleg , Lyashenko Alexandr
Published: October 2018

The method to increase the durability of high-strength cast iron with spherical graphite YAG:Nd-laser radiation is proposed. The results of studies in laser processing of cylindrical samples of high-strength cast iron grade of the VCH 70-3 are presented by the YAG:Nd-laser, working in pulse-periodic mode. Effect of the treatment with 1 kW YAG:Nd-laser on microhardness of high-strength cast iron has been investigated. More effective laser strengthening is found to be occurred by YAG:Nd-laser processing as compared with continuous CO2-laser one. The results showed that when processing of cast iron in general, the zone of laser influence consists of the reflow zone and the zone of quenching from the solid state. The optimal values of parameters of the hardened layer in the radiation by the solid-state YAG:Nd laser are considered. It is shown that under fluence of laser radiation fluence more than 28 j/mm2 is occured the surface melting of cast iron.
The use of nanomodified heat storage materials for thermal stabilization in the engineering and aerospace industry as a solution for economy
Authors: Shchegolkov Alexander , Shchegolkov Aleksei , Demidova Alevtina
Published: October 2018

The paper presents studies on the use of nanomodified materials with phase transitions. The rmostable heat exchange devices based on materials modified with carbon nanotubes allowing to control thermal contact have been developed. It is established that through a controlled thermal contact it is possible to provide a heat flux of up to 100 [kW·m-2 ]. The application of heat-resistance storage material in technical devices such as self-rescuers is justified. The efficiency of thermal control is established, since the temperature after the heat exchanger is reduced to 40 ° C at an incoming temperature of about 100 °C.
Nanomaterials in the power engineering industry: market trends and application prospects
Authors: Inshakova Elena , Inshakova Agnessa
Published: October 2018

The increase in the global consumption of marketed energy from all fuel sources (except coal) is regarded as a key factor driving power engineering industry (PEI) market growth. The absence of radical change in the structure of investment in PEI until 2030, with domination of investing equipment for the thermal power industry (with the exception of the year 2020) along with the essential growth of investment in the nuclear power industry is stated in the article. The authors focus on the significant potential of nanomaterials development and application for providing the PEI growth based on the new technological solutions and optimized technologies. Most widely used nanomaterials in the PEI worldwide, major fields and promising areas of nanomaterials application in the industry aimed at improving technology of the equipment’s fuel and structural elements construction, increasing efficiency of existing equipment, and developing renewable energy sector are examined. Contemporary trends and prospects for the PEI selected nanomaterials markets, their key players, positive and negative factors of market growth are identified.
Multiparameter method of surface hardening quality testing
Authors: Kostin Vladimir , Vasilenko Olga , Byzov Alexander
Published: October 2018

Measurements of the magnetic characteristics (coercive force, residual induction, induction of saturation) of objects that had different thicknesses of the hardened layer were made. The influence of an unstressed core on the measurement results, as well as the depth of the strengthened layer on the shape of the hysteresis loop, is investigated. The conclusion is made that it is possible to estimate the properties of a hardened layer by means of a single measurement with the help of the hardware-software system DIUS-1.15M
The method of smelting metals from charge with low metal content in a furnace with bottom electrodes and the first laboratory studies
Authors: Kazak Oleg , Starodumov Ilya
Published: October 2018

Liquid phase smelting reduction process for utilization of ferrous waste in the electric furnace with stationary bottom electrodes by carbon-thermal reduction is proposed and tested in laboratory conditions. The principal possibility of melting and reduction of iron heat generated in the slag bath between the bottom electrodes is shown.
Development verification of coatings made from porous ceramic-matrix composite materials
Authors: Reznik Sergey , Prosuntsov Pavel , Mikhaylovskiy Konstantin
Published: October 2018

The paper presents methodology and results of tests conducted for porous carbon ceramic specimens on a high-temperature gas dynamic facility to simulate real operating conditions for heat shields. The structure of the materials before and after tests is compared.
Modeling the run of a control program for turning a GTE disk compressor workpiece on a CTX Alpha 500 virtual dual-spindle CNC lathe
Authors: Ryazanov Aleksandr , Shvetsov Aleksey
Published: October 2018

The paper discusses a way to minimize the machine time to debug a control program. We propose performing most of the debugging on a 3D copy of a CNC metal-cutting machine. We herein present an example of how a compressor disk turning control program could be created and verified by a CTX alpha 500 virtual machine using Sinumerik 840D CNC system.
Profiles of critical states in diagnostics of controlled processes
Authors: Dubovik Sergey , Kabanov Aleksey
Published: October 2018

The forecasting problem of critical states of controlled processes is considered. The large deviations of controlled process from some regular state is the basis of forecasting. The main tool for the analysis of large deviations and prediction of critical states is asymptotic methods. The forecasting problem is reduced to the Lagrange-Pontryagin optimal control problem that in some conditions has a unique solution in the form of quasipotential. Based on quasipotential it is possible to build an effective prediction of critical states of controlled process.
Multi-server queue with batch arrivals
Authors: Korolkova Liubov , Mashrabov Nematulla , Murzin Alexandr
Published: October 2018

A multi-server queueing system, that is loaded continuously in certain periods of time and which functions for a certain amount of time allocated for the functioning of the system, is considered. Based on the renewal theory, an expression is obtained for the distribution density of the number of arrivals served herewith the service time for each server can be different. In the numerical example, the distributions of the number of services for the systems consisting of one, two, five servers are obtained. The approach to optimization of the queue using the stochastic model of supply and demand is outlined. According to the model, the distributions of the number of services, the queue length as the number of unused arrivals, the number of idle servers as the number of unused services are calculated. Each of these values corresponds to the cost. Knowledge of the distribution functions of the model indicators makes it possible to calculate the cost parameters with dependence of unit costs on the number of servers. The optimal number of servers can be selected from the condition of the maximum of the total average cost.
Calculation of magnetic devices cleaning coolants in the agro–industrial complex
Authors: Avdeyev Boris , Prosvirnin Victor , Dema Roman R.
Published: October 2018

Traditional ways of cleaning of cooling lubricants in agrarian–industrial complex are considered in the article. Experimental data on the presence of magnetic impurities and its fractional composition as a result of parts machining on machines with the use of cooling lubricants are cited. Combined devices based on the combination of traditional methods for cleaning technical fluids have been used to intensify the cleaning process. The use of such combined cleaning methods is grounded, the forces effecting on the particles in the process of separation – coagulation forces, magnetic deposition, and medium resistance – are considered. The mathematical model of the coagulation process of two particles having similar size in a homogeneous magnetic field is made up. However, it is impossible to solve the obtained system even by a numerical method with unknown initial conditions. In this connection, the inverse problem is proposed. The physical significance of the effect of forces is as follows: a floccule consisting of two particles is destroyed under the effect of coagulation forces; the resistance of the medium prevents it. Its numerical solution allows finding the main dynamic characteristics of particle coagulation: the speed and distance from which they interact.
Development of robotics technologies in agriculture
Authors: Mashkov Konstantin , Rubtsov Vasyliy , Rubtsov Ivan
Published: October 2018

The assessment of the resource potential of agriculture of the Russian Federation was given. The main factors that determine a more complete use of the potential available in the industry were defined. The conditions for the introduction of modern technologies of “Precision farming" were described. The heterogeneous composition of the group maintenance of agricultural land was identified. The stages of development of robotics technologies in agriculture are considered. The problematic technology of unmanned agriculture was given. The socio-economic effects that can be achieved when implementing the proposed measures are described. The vector of development of agricultural robotics was given.
Features of designing feeding hoppers of loose materials of low productivity in agriculture
Authors: Timoleanov Konstantin , Savenkov Dmitry , Gorgadze Lyubov
Published: October 2018

Hopper installations are the main constituent of machines units of agricultural production. They are used in operations connected with storing, transporting and processing of loose grain materials. In spite of the simplicity of construction they have a serious drawback relating to a certain loose material property. The loose material while being outflowed from the capacity forms arched (bridge) structures that prevent a normal gravitational outflow resulting in it acquiring an unstable character. In this work, some methodology is given to calculate a vibrational dome breaking device with a lateral outlet opening that provides a steady supply of grain of different moisture. The facility developed enabled to achieve a steady grain outflow of various moisture from bins with lateral output openings under conditions that had never been possible before. The device developed enabled to achieve a steady grain outflow of various moisture from bins with lateral output openings under conditions that had never been possible before. In general, the results obtained show that the application of dome breaking device can be used in hopper installations to ensure steady grain outflow of various moisture and low productivity.
A PTAS for single-machine scheduling with release dates and job delivery to minimize makespan
Authors: Lu Lingfa , Zhang Liqi
Published: October 2018

We consider the single-machine scheduling problem with release dates and job delivery to minimize makespan. Preemption is not allowed in the processing of the jobs. All jobs are first processed on a single machine and then delivered by a capacitated vehicle to a single customer. The vehicle can deliver at most c ≥ 1 jobs in each shipment. The round-trip transportation time between the machine and customer is a constant T > 0. The problem was proved to be strongly NP-hard and a 3/2-approximation algorithm was presented in the literature. In this paper we provide a polynomial-time approximation scheme (PTAS) for the problem.
Hormontherapie in der Peri- und Postmenopause
Authors: Meyer Sophie , Seifert-Klauss Vanadin
Published: October 2018

The recently published 18-year-follow-up of the WHI-study might resolve the long-standing dispute about hormone therapy, possibly reconciling the opposing parties attributing life-threatening risks to either the administration or the withholding of hormone therapy. 16 608 women without hysterectomy had taken either combined hormone therapy with estrogen and progestin or placebo for an average of 5.2 years, while 10 739 women after hysterectomy (and bilateral ovarectomy in 40 %) had taken either estrogen therapy alone or placebo for an average of 7 years. 7489 deaths were recorded until 2014. Over both studies, mortality was 27.1 % after hormone therapy and 27.6 % after placebo. New findings on perimenopause can help towards phase-adapted and complaint-targeted hormone therapy in the future.
Troubleshooting bei Patienten mit Herzschrittmacher und ICD
Authors: Meyer zu Vilsendorf Dorothee , Hansky Bert , Baumann Philipp , Stellbrink Christoph
Published: October 2018

Because of the growing number of implanted cardiac pacemakers and defibrillators and the ever-increasing complexity of these devices a fundamental knowledge of device malfunctions is of utmost importance even for the non-cardiology physician. Apart from hardware problems such as device infection, lead fracture or dislocation, basic knowledge of the pacemaker sensing and pacing algorithms is also necessary in order to judge the stimulation behavior in different clinical settings. With this respect, there are specific problems for antibradycardia and resynchronizing pacemakers as well as implantable defibrillators. This article gives an overview of the most common problems with cardiac pacemakers and defibrillators as well as the differential diagnostic and therapeutic management for the physician without specific training in arrhythmology.
Neue innovative Schrittmachersysteme – Kabellose und subkutane Implantate
Authors: Napp Andreas , Reith Sebastian
Published: October 2018

Conventional transvenous pacemaker and ICD-therapy is associated with significant lead- and pocket-related problems. Leadless pacemaker and subcutaneous ICD (S-ICD) therapies are innovative technologies, that avoid these complications. To date two leadless pacemaker systems have been implanted percutaneously for isolated right ventricular pacing, the Nanostim™ and the Micra™ device. The S-ICD represents an alternative to the transvenous ICD for primary and secondary prevention of sudden cardiac death. New multicomponent leadless pacemakers, as well as the combination of leadless pacemaker and S-ICD, are promising therapeutic options in the future. This review describes the state of the art of leadless pacing and S-ICD-therapy.
Umbilical Cord Blood Gas Analysis, Obstetric Performance and Perinatal Outcome
Authors: Ferreira Cátia Sofia , Melo Ângela , Fachada Ana Helena , Solheiro Helena , Nogueira Martins Nuno
Published: October 2018

Objective To analyze if umbilical artery pH (pHua) ≤7.00 and umbilical artery blood deficit (BDua) ≥12.00 mmol/L are good predictors of adverse neonatal outcomes.

Methods This was an observational, longitudinal and retrospective cohort study, conducted at the department of obstetrics and gynecology of Centro Hospitalar Tondela Viseu between September 2013 and September 2015. Total cohort and subgroup analysis were performed: group A—women with umbilical cord blood gas analysis (UCBGA) performed for non-reassuring fetal cardiotocographic patterns, placental abruption, or shoulder dystocia; and group B—all the others. Assays were made with the software SPSS for Windows, Versions 20.0 and 21.0 (IBM Corp., Armonk, NY, USA).

Results A total of 428 UCBGAs met the inclusion criteria. The group analysis revealed an association between group A and pHua ≤7.00, as well as between BDua ≥12.00 mmol/L and 1st minute Apgar score ≤4 (p = 0.011). After the application of the logistic regression models in the total cohort analysis, pHua ≤7.00 had an impact in the occurrence of acute neonatal hypoxia (odds ratio [OR]: 6.71; 95% confidence interval [CI]: 1.21–37.06; p = 0.029); multiparous women had a higher risk of delivering a newborn with first minute Apgar score ≤4 and acute neonatal hypoxia (OR: 5.38; 95% CI: 1.35–21.43; p = 0.017; and OR: 2.66; 95% CI: 1.03–6.89, p = 0.043, respectively); women who had urologic problems during pregnancy had a higher risk of delivering a newborn with 5th minute Apgar score ≤7 (OR: 15.17; 95% CI: 1.29–177.99; p = 0.030); and shoulder dystocia represented a 15 times higher risk of acute neonatal hypoxia (OR: 14.82; 95% CI: 2.20–99.60; p = 0.006).

Conclusion The pHua and the BDua are predictors of adverse neonatal outcome, and UCBGA is a useful tool for screening newborns at risk. Universal UCBGA should be considered for all deliveries, as it is an accurate screening test for neonatal hypoxia.
Torsion Does Not Affect Early Vein Graft Patency in the Rat Femoral Artery Model
Authors: Harb Amro , Levi Maxwell , Kozato Akio , Akelina Yelena , Strauch Robert
Published: October 2018

Background Torsion of vein grafts is a commonly cited reason for graft failure in clinical setting. Many microsurgery training courses have incorporated vein graft procedures in their curricula, and vein graft torsion is a common technical error made by the surgeons in these courses. To improve our understanding of the clinical reproducibility of practicing vein graft procedures in microsurgery training courses, this study aims to determine if torsion can lead to early vein graft failure in nonsurvival surgery rat models.

Methods Sprague-Dawley rats were divided into five cohorts with five rats per cohort for a total of 25 rats. Cohorts were labeled based on degree of vein graft torsion (0, 45, 90, 135, and 180 degrees). Torsion was created in the vein grafts at the distal arterial end by mismatching sutures placed between the proximal end of the vein graft and the distal arterial end. Vein graft patency was then verified 2 and 24 hours postoperation.

Results All vein grafts were patent 2 and 24 hours postoperation. At 2 hours, the average blood flow rate measurements for 0, 45, 90, 135, and 180 degrees of torsion were 0.37 ± 0.02, 0.38 ± 0.04, 0.34 ± 0.01, 0.33 ± 0.01, and 0.29 ± 0.02 mL/min, respectively. At 24 hours, they were 0.94 ± 0.07, 1.03 ± 0.15, 1.26 ± 0.22, 1.41 ± 0.11, and 0.89 ± 0.15 mL/min, respectively.

Conclusion Torsion of up to 180 degrees does not affect early vein graft patency in rat models. To improve the clinical reproducibility of practicing vein graft procedures in rat models, we suggest that microsurgery instructors assess vein graft torsion prior to clamp release, as vessel torsion does not seem to affect graft patency once the clamps are removed.
Takotsubo cardiomyopathy and major depressive disorder
Authors: Connemann B. J. , Dahme T. , Tesfay T. , Gahr M. , Elsayed M.
Published: October 2018

Gegenstand und Ziel: Das Tako-Tsubo-Syndrom (TTS) ähnelt klinisch einem akuten Myokardinfarkt und ist häufig mit emotionalem oder physischem Stress assoziiert. Patienten mit TTS stellen sich daher häufig zuerst in einer psychiatrischen Klinik vor; dies kann die adäquate Diagnostik und Therapie verzögern, insbesondere wenn der Psychiater nicht mit TTS vertraut ist. Material und Methoden: Ein klinischer Fall eines TTS wird vorgestellt und diskutiert und das Krankheitsbild des TTS vorgestellt. Ergebnisse: Eine 43-jährige Patientin stellte sich notfallmäßig in unserer psychiatrischen Ambulanz vor. Unmittelbar vor der Vorstellung war es am Arbeitsplatz zu erheblicher Schikane der Patientin gekommen (Mobbing). Zum Vorstellungszeitpunkt beklagte die Patientin akute linksthorakale Schmerzen sowie seit einigen Wochen bestehend gedrückte Stimmung, verminderten Antrieb, Anhedonie, generalisierte Ängste und Schlafprobleme. Das Elektrokardiogramm (EKG) war unauffällig, das Serumtroponin jedoch deutlich erhöht. Die Patientin wurde daraufhin in die Abteilung für Kardiologie verlegt. Herzkatheter und Kardio-MRT zeigten eine apikale Ballonbildung (apical ballooning) und linksventrikuläre Dysfunktion, passend zu TTS. Schlussfolgerungen und klinische Relevanz: Bei Patienten mit akuter Psychopathologie und kardialen und/oder thorakalen Symptomen sollten ein EKG und eine Bestimmung des Serumtroponins durchgeführt werden.
Endoprothetik des Schultergelenkes bei der rheumatoiden Arthritis und anderen entzündlich rheumatischen Gelenkkrankheiten
Authors: Niemeier A. , Rüther W.
Published: October 2018

Auch schwere rheumatische Veränderungen des Glenohumeralgelenkes und seiner periartikulären Weichgewebe lassen sich erfolgreich durch die Schulterendoprothetik behandeln. Das Spektrum der chirurgischen Optionen ist breit. Die Endoprothetik bietet verschiedene Prothesentypen mit jeweils spezifischen Vor- und Nachteilen. Die rheumatische Arthritis (RA) und andere entzündlichrheumatische Krankheiten weisen gravierende Unterschiede zu den Arthrosen auf, das betrifft die Indikationsstellung, die Operationsvorbereitung, die Durchführung der Operation und die Nachbehandlung. Die Indikationsstellung und die Operation sollten in der Hand eines erfahrenen Rheumachirurgen liegen, der die Spezifika der entzündlich rheumatischen Erkrankungen in Abgrenzung zur Arthrose dezidiert erfahren hat und in Kenntnis des gesamten Spektrums der Differenzialindikationen und Prothesenmodelle eine individuelle Entscheidung für und mit dem Patienten trifft.
Gain dynamics in a heterogeneous terahertz quantum cascade laser
Authors: Derntl C. G. , Scalari G. , Bachmann D. , Beck M. , Faist J. , Unterrainer K. , Darmo J.
Published: October 2018

The gain recovery time of a heterogeneous active region terahertz quantum cascade laser is studied by terahertz-pump-terahertz-probe spectroscopy. The investigated active region, which is based on a bound-to-continuum optical transition with an optical phonon assisted extraction, exhibits a gain recovery time in the range of 34–50 ps dependent on the operation condition of the laser. The recovery time gets shorter for stronger pumping of the laser while the recovery dynamics slows down with increasing operation temperature. These results indicate the important role of the intracavity light intensity for the fast gain recovery.
Asymmetric flexural wave transmission based on dual-layer elastic gradient metasurfaces
Authors: Cao Liyun , Xu Yanlong , Assouar Badreddine , Yang Zhichun
Published: October 2018

Traditional asymmetric transmission of elastic waves is mostly based on mode conversion, which presents a real challenge to get pure-mode elastic waves. In this letter, without the aid of mode conversion, we present an innovative concept of asymmetric flexural wave transmission within a wide frequency band, based on dual-layer elastic wave gradient metasurfaces. According to the generalized Snell's law, we theoretically and numerically design and experimentally demonstrate the asymmetric flexural wave transmission by tuning the supercell lengths of dual-layer metasurfaces. The experimental results confirm that the proposed design provides a wide effective frequency band feature, which agrees well with the theoretical analysis and predictions. Our concept offers the flexibility to control the wave energy flow, opening the route to pragmatic applications in many fields, such as ultrasonic detection, energy harvesting, and vibration control.
Numerical simulation of polymer grout diffusion in a single fracture
Authors: Hao Meimei , Li Xiaolong , Zhong Yanhui , Zhang Bei , Jin Di , Chen Guanggong
Published: October 2018

Polyurethane grouting materials, a type of expansible grout, has played a significant role in the rehabilitation of public infrastructures, such as lifting the slab in a road and reinforcing the broken wall rocks in a tunnel. Due to the unique expansion characteristic of polyurethane materials induced by the chemical reaction, its diffusion mechanism in rock fracture is rather complicated. Based on a numerical method presented in a previous paper, the diffusion law of expansible grout in a single fracture is studied considering the time-varying density and viscosity of the grout tested by experiments. The grout diffusion radius, pressure distribution and velocity field are calculated by the numerical model combining the finite volume method (FVM) and volume-of-fluid (VOF) method. Taking the gel time into account, the characteristics of flow field distribution during the grout movement process are investigated on five different cases and the influences of grouting quantity and fracture aperture on grout diffusion behavior are analyzed, which can reveal some diffusion law of expansible grout in a single water-free fracture.
A mechanically driven magnetic particle imaging scanner
Authors: Bagheri H. , Kierans C. A. , Nelson K. J. , Andrade B. A. , Wong C. L. , Frederick A. L. , Hayden M. E.
Published: October 2018

We describe and demonstrate an approach to magnetic particle imaging in which particle excitation and field free point (FFP) manipulation are decoupled from one another. The additional degrees of freedom enabled by this decoupling suggest alternative strategies for studying and exploiting contrast mechanisms, optimizing image quality and resolution, and device-size scaling. The prototype instrument we describe uses rotating arrays of permanent magnets to scan the FFP through the field of view and current-driven oscillating magnetic fields to elicit non-linear magnetization responses from superparamagnetic nanoparticles. Narrow-band phase sensitive detection of these responses at one or more harmonics of the excitation field provides a rich source of information from which images can be reconstructed. Images generated from data acquired using this instrument are presented, demonstrating the resolution of features with sub-millimetre dimensions.
Laboratory diagnosis of human infections transmitted by ticks, fleas, mites and lice in Australia
Authors: Stenos John , Graves Stephen R
Published: October 2018

A wide range of human pathogens (viruses, bacteria, protozoa) are transmitted by ticks, fleas, mites and lice worldwide. Some of these infections occur in Australia1, whereas others appear to be absent, although they may occur in returned travellers. The key to diagnosis is two-fold: recognition of the possibility of a vector-borne infection by the treating doctor and confirmation of the diagnosis in a diagnostic, microbiology laboratory. Laboratory diagnostic assays include culture (used rarely), nucleic acid amplification (used increasingly) and serology (used often).
Habitat suitability and connectivity for an endangered brown bear population in the Iranian Caucasus
Authors: Habibzadeh N. , Ashrafzadeh M. R.
Published: October 2018

Context
The identification of suitable habitats and the assessment of connectivity are important to preserve key areas for small isolated, endangered populations. The brown bear, Ursus arctos, needs connectivity to supply the primary habitat requirements including food, water, shelter and space and to provide gene flow among all populations in the Iranian Caucasus.

Aims
In the present study, we investigated the status and habitat requirements of an endangered brown bear population within the Iranian Caucasus.

Methods
We applied an approach of consensus species distribution modelling to estimate the distribution of suitable habitats for brown bears using uncorrelated environmental variables. We then used the concept of circuit theory on resultant breeding patches to evaluate regional patterns of connectivity among these patches.

Key results
We predicted that ~9.10% of the study area is suitable for the brown bear at present. Ten patches (7.95% of the study area) were detected as suitable for breeding populations, where some populations are not able to survive without connectivity. The results indicated that habitat connectivity is sometimes widely affected by a high concentration of human activities such as roads, settlements and mining activities. Our findings showed that existing conservation areas could not safeguard the connectivity of brown bear habitats across the Iranian Caucasus.

Conclusions
Our results can help target fine-scaled planning approaches for the maintenance of bear meta-population structure, as well as facilitate the movement of individuals by protecting different landscape features.

Implications
The populations of brown bear are among the first to be harmed by the loss of habitat and connectivity, and, thus, this species is an appropriate focal species for linkage design that is beneficial for threatened populations of other co-existing species such as Persian leopard, grey wolf and Eurasian lynx. Moreover, the brown bear is among the most popular flagship species for conservation planning, which might increase public support for the restoration of habitat and linkages.