bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of linear programming to optimize the cost-benefit criterion in production processes
Authors: Krynke Marek , Mielczarek Krzysztof
Published: July 2018

In this paper linear programming was shortly characterized. The implementation of some basic functions for Octave have been presented. It is the GNU General Public License program for the optimization the cost-benefit criterion in production processes. A problem of dividing production tasks between workstations was presented in way that the cost of the realization was the smallest. The final score of the course was obtained the computational environment Octave using the GLPK (GNU Linear Programming Kit) function.
Optimizing the mechanical device of a mono-axial sun tracking mechanism
Authors: Alexandru Cătălin
Published: July 2018

The paper deals with the dynamic optimization of the mechanical device for a mono-axial sun tracking system, with application for photovoltaic and solar-thermal systems, which convert the solar radiation in electrical or respectively thermal energy. The actuating of the mono-axial tracking mechanism is carried out by using a linear actuator, the optimization study intending to determine the optimal configuration of the mechanism with the aim to minimize the motor force developed by actuator in order to perform the imposed step-by-step tracking algorithm (motion law). The design variables in the optimal design process are represented by the global coordinates of the connection points of the linear actuator to the adjacent parts (the solar panel and the fixed support). The optimization study is conducted in virtual prototyping environment.
Dynamical analysis of a 2-degrees of freedom spatial pendulum
Authors: Alaci Stelian , Ciornei Florina-Carmen , Siretean Sorinel-Toderas , Ciornei Mariana-Catalina , Andrei Ţibu Gabriel
Published: July 2018

A spatial pendulum with the vertical immobile axis and horizontal mobile axis is studied and the differential equations of motion are obtained applying the method of Lagrange equations. The equations of motion were obtained for the general case; the only simplifying hypothesis consists in neglecting the principal moments of inertia about the axes normal to the oscillation axes. The system of nonlinear differential equations was numerically integrated. The correctness of the obtained solutions was corroborated to the dynamical simulation of the motion via dynamical analysis software. The perfect concordance between the two solutions proves the rightness of the equations obtained.
Study regarding the influence of airbag deployment time on the occupant injury level during a frontal vehicle collision
Authors: Ionut Radu Alexandru , Cofaru Corneliu , Tolea Bogdan , Dima Dragoş
Published: July 2018

The aim of this paper was to analyse the influence of airbag deployment delay upon the head of the occupant in the case of frontal collision using simulations in PC Crash and MADYMO dummy as the occupant. The study will also take into account the pretension delay of the seat-belt which is activated along with the airbag. Frontal airbags on both the passenger and the driver were analysed including the occupant kinematics during the collision. Also, to validate the simulation, a comparison was done with a real crash test. We predict that by increasing the delay of deployment, the head acceleration will increase due to the fact the head travels close to the instrument panel/steering wheel, and the force of the airbag will generate a significant acceleration upon the head. To better assess the potential injury of the occupant, the head injury criteria (HIC) will be calculated and correlated with the Abbreviated injury scale (AIS) code.
Analysis of the Evolution of the Number of Fatal Road Accidents in Romania
Authors: Tarnu Lucian , Deac Cristian
Published: July 2018

Fatal car accidents are a major issue of concern for both the police, the local and regional administrations and all those involved in providing road safety. The current paper presents an analysis of the number of fatal car accidents on Romanian roads, in the context of the Road Safety Programme of the European Commission, emphasising the efforts being made in this regard, the areas where road safety is still lacking and recommending some measures for improving the situation.
Research on combustion process of gasoline homogenous charge compression ignition engine
Authors: Cofaru Corneliu , Virginia Popescu Mihaela
Published: July 2018

The paper presents the research designed to develop a HCCI (Homogenous Charge Compression Ignition) engine starting from a spark ignition engine platform. The chosen test engine was a single cylinder, four strokes provided with a carburettor. The results of experimental research data obtained on this version were used as a baseline for the next phase of the research. In order to obtain the HCCI configuration, the engine was modified, as follows: the compression ratio was increased from 9.7 to 11.5 to ensure that the air – fuel mixture auto-ignite and to improve the engine efficiency; the carburettor was replaced by a direct fuel injection system in order to control precisely the fuel mass per cycle taking into account the measured intake air-mass; the valves shape were modified to provide a safety engine operation by ensuring the provision of sufficient clearance beetween the valve and the piston; the exchange gas system was changed from fixed timing to variable valve timing to have the possibilities of modification of quantities of trapped burnt gases. The cylinder processes were simulated on virtual model. The experimental research works were focused on determining the parameters which control the combustion timing of HCCI engine to obtain the best energetic and ecologic parameters.
On the benchmarking of friction in timing chains
Authors: Jurj Lenard , Velicu Radu
Published: July 2018

This paper is dealing with the evaluation of friction in timing chains. Benchmarking friction is based on the experimentally determined friction losses in basic chain drives with transmission ratio i=1. This friction is not including friction losses in bearings. These results should be used, in the simplest manner, in order to evaluate friction in timing chains (i = 2). We are presenting the theoretical approach and experimental validation that have been developed for the timing chain drives, with transmission ratio i = 2. Friction losses are presented as resistant friction torques at the input shaft, depending on input rotational speed and tensioning force in the chain drive.
Modeling in ADAMS of a 6R industrial robot
Authors: Ratiu Mariana , Rus Alexandru , Loredana Balas Monica
Published: July 2018

In this paper, we present the first steps in the process of the modeling in ADAMS MBS of MSC software of the mechanical system of an articulated robot, with six revolute joints. The geometric 3D CAD model of the robot, identical to the real model, in the PARASOLID format, is imported into ADAMS/View and then are presented the necessary steps for building the kinematic model of the robot. We conducted this work, in order to help us in our future research, which will consist of kinematic and dynamic analysis and optimization of the robot motion.
Automatic fuel tank monitoring, tracking & theft detection system
Authors: Komal D/o Shoukat Ali Khuwaja , Arif Ali Brohi , Mihalca Vlad O. , Radu Cătălin Țarcă
Published: July 2018

This paper presents the design, implementation and characterization of a hardware platform for Fuel Management System (FMS) for fuel carrying vehicles. The primary design goal is to devise a system capable of monitoring the fuel level in real time. This system is proposed for fuel carrying road tankers which carry fuel from oil depots to end users such as petrol-stations. This system is based on hardware as well as software. The hardware part consists of fuel level circuits, on-board Arduino, GSM and GPS modules. While the software part consists of LabView for Database purposes. This system offers an Automatic Electronic System (AES) which replaces manual monitoring of fuel. This system measures fuel volume and sends measured volume to the owner’s mobile as well as owner’s computer through GSM network. It also provides a technique for detecting theft or fraud incidents in case of fuel theft or fuel leakage. Additionally the system can track the location of each fuel carrying tanker in order to locate the place of any incident that could have occurred. This system allows for an automated analysis and monitoring of fuel level, having a reduced cost due to affordable and easy-to-acquire electronic components.
Three phase induction motor modelling and control using vector control in LabVIEW
Authors: Wadee Khoury , Aram Nasser , Péter Tamás Szemes
Published: July 2018

In this paper, a speed control system for a three-phase induction motor was modelled and designed within LabVIEW software environment. After structuring the dynamical model of the motor, a current controller was developed to stabilize the system and avoid a wind-up situation. Then, a speed controller was designed, using PID and Field Weakening techniques, to generate the reference current values. The field-weakening algorithm is used to achieve stability at speeds that are higher than the nominal one. An estimator is used to calculate the flux angle and the electro-mechanical speed of the motor. As a result, the system achieved the desired speed with good transient and steady state responses. In addition, the system proved to be robust when the torque load is applied in all cases.
The maintenance, commissioning of FANUC M-1iA 0.5A type selecting robot and implementation of iRVision picture-recognizing procedure
Authors: Korsoveczki Gyula , Husi Géza , István Erdei Timotei
Published: July 2018

The topic of the given project is based on the maintenance, commissioning and implementation of iRVision picture-recognizing procedure, and the operation of the associated program of the FANUC M-1iA 0.5A type delta tripod designed selecting robot that can be found at the Mechatronics Department, Engineering Faculty of the University of Debrecen. Keywords — FANUC; M-1iA 0.5A; delta tripod; robot; iRVision; picture-recognizing
T3D end milling finite element thermal analysis
Authors: Mitrović Andjelija. , Kovač Pavel. , Kulundžić Nenad. , Savković Borislav. , Mankova Ildiko.
Published: July 2018

The paper presents a modern approach to the phenomenon of thermal analysis in end milling by the finite element method. 3D model of the end mill and work-piece was created in the software package SolidWorks. In order to predict the occurrence of thermal phenomena in milling process software package Third Wave AdvatEdge was used. Influence of cutting speed on the temperature in cutting zone was modelled and analyzed.
Contribution for increasing the manufacturing companies productivity using a tracking and planning production program
Authors: Francisc Pişec Iaroslav , Pop Alin
Published: July 2018

In this paper is presented roughly a tracking and planning production program. The major challenge for manufacturing companies is to have the highest efficiency regarding the productivity. For this reason, the best way to achieve this is to track all elements from production process and to plan all phases as well as possible. The method used for planning production, is the Critical Path Method (CPM) because this kind of planning method determinates in advance the time of fabrications of complex parts. Using this tracking and planning production program, the companies can check the machine tools workload, can analyse the capacity, can assign the proper equipment for part’s fabrication, can estimate the delivering products time and also the cost of it. One of the advantages is that this information is provided on real time.
The lubricants' parameters monitoring and data collecting
Authors: Grebenişan Gavril , Salem Nazzal , Bogdan Sanda
Published: July 2018

This approach is focused on Machine Intelligence for Diagnosis Automation, a research program, which promotes « preventative maintenance in manufacturing plants through the development of a fully automated prototype for oil analysis and fault prediction. The prototype is based on Artificial Intelligence (A.I.) software and online hardware ». Monitoring the condition of lubricants requires the examination of the physical, chemical and additive states, which maintain the quality of the lubricants, which is necessary for the proper functioning of the equipment. A lubricant monitoring program, especially from a qualitative point of view, will need to focus on both machine tool wear and degradation of lubricants, as well as on detecting and describing abnormal working conditions for both lubricants and machine parts. This goal can be satisfied by examining all the oils used in a company by completing laboratory tests to generate steps and acceptance classes, as well as unplanned contingency analyzes. These laboratory tests can be concentrated and classified into technology-based data sheets based on test-based information and test results, ultimately constituting consistent databases needed to generate monitoring and prevention reports. Data on the condition of the oil parameters used in the hydraulic system for lubricating machine tools have been collected during six months. The data as matrix organized, with 258648 rows (observations) and 21 columns (parameters).
Development of the method of direct temperature measurement for gear cutting of cylindrical gears by hob milling
Authors: Sovilj-Nikić Sandra , Sovilj Bogdan , Ješić Dušan , Blanuša Vladimir , Tonkonogyy Vladimir M. , Bovnegra Liubov
Published: July 2018

The availability, adaptability, reliability and productivity of modern industrial complexes, maintenance costs, energy costs and industrial production costs depend also on the intensity of wear of the elements of tribo-mechanical systems. Gear cutting operations are usually a bottleneck of production, especially in higher types of production. Therefore, the necessity of researching the process of gear cutting by hob milling is obvious. In the paper a part of the results related to the possibility of direct measurement of the temperature in a very complex process of gear cutting of cylindrical gears by hob milling is given.
The influence of dividend policy on the volatility of shares in the Romanian equity capital market
Authors: Cristea Ciprian , Cristea Maria
Published: July 2018

Dividend policy is one of the most debated topics in corporate finance and, at the same time, it represents an important issue from the perspective of both the managers of the firm and the investors. To the best of our knowledge, the literature regarding establishing the relationship between dividend policy and share price volatility of non-financial companies listed on Romanian stock market remains inexistent. This study attempts to identify how the share price volatility of non-financial companies listed on the Bucharest Stock Exchange for a period of sixteen years from 2002 and 2017 is influenced by corporate dividend policy. Results from a cross sectional multiple regression analysis revealed a negative effect of the two components of the dividend policy on the share price volatility. The results support the idea that the lower the dividend yield, the higher the risk to be faced by the shareholder. Growth in assets and share price were negatively related. Positive relationship between firm size and debt ratio to price volatility were identified. However, there was no significant relationship found between earning volatility and price volatility in the Romanian stock market.
Occupational health and safety risk management
Authors: Oarga Ioan-Florin , Rațiu Mariana , Oarga Ioan-Tudor
Published: July 2018

The ongoing industrial revolution also includes the health and safety domain, which assists this development process. The participants and beneficiaries of this revolution don’t have to endure a lowering of the protection levels from the beginning of it. Consequently, the health and safety domain needs to play its role in this historical stage. The risks of injury and illness are managed from the beginning, when the technological processes are being developed, on each production stage, until the end of every technological process. In order to achieve this, the professional risks must be identified, quantified, ranked and evaluated such that, the elaborated measures will eliminate or decrease the risks from the source. This control process of occupational health and safety risks of injury or illness uses documents which are applicable to any organization. These documents are legally required in each state, being instruments of the organization management, working like a system along with all other documents.
Strategic management problems in Romanian small and medium-sized enterprises
Authors: Moraru Gina-Maria , Popa Daniela
Published: July 2018

The aim of the paper is to discover several of the strategic management problems that affect the most of Romanian small and medium-sized enterprises. The study presented here is only a part from a larger research developed by us during the last five years, research oriented towards sustainable development opportunities of these enterprises. Technological revolution, knowledge management and global expansion of big companies are just a few challenges to which small businesses have to cope. For this, their strategic management needs to take into account the turbulent business environment, to anticipate and to carry out correctly and in time the necessary changes in the organization. Unfortunately, our study has found gaps in the use of key strategic management tools and in the balanced use of resources in small Romanian firms.
Analysis of supporting indicators for innovation in Romania compared to neighboring EU countries
Authors: Constantin Bungau , Ion Cosmin Gherghea
Published: July 2018

The paper presents a comparative study of indicators which targeting the facilities and support for the innovation process. The study targets indicators regarding human resources, support structure / infrastructure and legislative provisions. The analysis is carried out over the last 5 years, comparing the indicators in Romania and the neighboring countries (Bulgaria, Hungary, Austria, Slovakia and Poland) and highly developed countries (Germany and France). Based on this study, will be drawing conclusions for improvement of these indicators. The indicators that will be taken into consideration are: Availability of scientists and engineers, Researchers, Quality of the education system, Researchers in Research and Development, Research and development expenditure, Firm-level technology absorption, University-industry collaboration in Research & Development, Quality of scientific research institutions, Gross domestic spending on Research and Development, Property rights, Intellectual property protection.
The asymmetry of income distribution between stakeholders within the framework of industrial park structures
Authors: Plakhin Andrey , Semenets Igor , Ogorodnikova Ekaterina
Published: July 2018

The purpose of this article is to prove the author‘s hypothesis about the formation of an asymmetry in the distribution of income of stakeholders in the industrial park structure, due to the increased impact of economies of scale on the activities of the residents of the park. In this article, the authors propose a model of income distribution, on the basis of which the prevailing role of the state as the beneficiary of the results of activity within the framework of the park structure was proved. It also indicates a clear asymmetry of income distribution, formed due to economies of scale between other stakeholders. The revealed characteristics can be claimed for the justification of concepts and other documents of a program nature in the formation of industrial park structures.
Allocation of logistic risk-investment in public-private-partnership – use of fuzzy TOPSIS method
Authors: Kauf Sabina , Tłuczak Agnieszka
Published: July 2018

Appropriate risk assessment related to the project, and then its distribution between partners is the core of cooperation in the framework of public-private partnership (PPP). Risk analysis for investment project in the PPP formula includes: preliminary identification of risks associated with the investment, preliminary assessment and forecast of probability of occurrence of risks in the recommended option of investment implementation, initial analysis of the distribution of risks between a public and private entity depending on the legal and organizational model adopted, including the determination of the appropriate separation between the parties to the contract. The article presents the possibility of using multicriteria methods, in particular fuzzy TOPSIS, for risk assessment and selection of the best contractor for a given project under PPP.
Numerical investigation on the forming behaviour of stainless/carbon steel bimetal composite
Authors: Li Zhou , Zhao Jingwei , Zhang Qingfeng , Jiao Sihai , Jiang Zhengyi
Published: July 2018

Bimetal composites have wide applications due to their excellent overall performance and relatively low comprehensive cost. The aim of this study is to investigate the forming behaviour of stainless/carbon steel bimetal composite during stamping by finite element method (FEM). In this work, the bonding interface of bimetal composite sheet was assumed to be perfect without delamination during the plastic forming process for simplicity. Uniaxial tensile tests on base metal (carbon steel) and compositing metal (stainless steel) were first carried out, respectively, in order to obtain the tensile properties of each of the component materials required in the forming simulation. Processing variables, including the layer stacking sequence, relative thickness ratios of two layers and friction were considered, and their effects on the distributions of circumferential stress and thickness strain were analysed. The bimetal composite sheet was set as the eight-node solid elements in the developed FEM model, which is effective for evaluating the distributions of circumferential stress and thickness strain, and predicting the high-risk region of necking during the stamping of bimetal composites. The simulation results can be used as an evaluation indicator of the capability of forming machine to ensure the bimetal composite can be safely formed.
Light and eco-friendly structure design of an instant noodle bowl
Authors: Fang Jiunn , Chen Po-Chuan
Published: July 2018

Instant noodles have become a very common food in recent years, and because of its convenience and affordability, it is now one of the most profitable products in the food industry. While it is a very convenient food product to carry around, its packaging tends to be inconvenient and not eco-friendly. The packaging of instant noodles can be categorized into two different types: The first is small, and very light, packed in plastic bags, requiring that customers supply their own bowl in order to enjoy the food; the other is packed in a paper, or Styrofoam bowl, usually with additional space in the bowl for customers to add water. The dimensions of the bowl make it less portable, and the construction materials are not eco-friendly. We build a model design that combines the benefits of each packaging type (Fig.2). The size remains as small as the plastic bag type, while simultaneously having the expandable space of the bowl type. The proposed model is made compact during shipping, but its foldable design allows the customer to readily reconstruct it into a bowl for use. Using recycled paper and PE film for materials, we have ensured that, with the use of special recycling technology, the packaging is 100% recyclable. The result is an eco-friendly, light, and purposeful design.
Self-loosening of 3D printed bolted joints for engineering applications
Authors: Wi Jun-Hee , Lee Kwang-Hee , Lee Chul-Hee
Published: July 2018

A bolt joint is a simple element that joins mechanical components. Self-loosening of bolted joints occurs due to the vibrations caused by motors and engines, resulting in the breakage of machines, and potentially serious safety problems. Recently, developments in 3D printing technologies have enabled the fabrication of detailed components. These technologies can be used for producing fasteners using 3D printed bolts. Many researchers have proposed a theoretical model for self-loosening of the bolt, and experimental studies on the self-loosening phenomenon have been advanced. However, studies on the self-loosening of 3D printed bolts have not been conducted. Therefore, it aims to confirm the self-loosening phenomenon and the safety of 3D printed bolts through experiments and finite element simulation. A lateral vibration test system is constructed and self-loosening of the bolt is evaluated by observing the axial force according to the vibration cycle by using a strain gauge. This study compared the self-loosening of 3D printed bolts and steel bolts by changing the preload and amplitude. In addition, the experimental results are verified through finite element simulation. Through this study, it is expected that 3D printed bolts will be used more frequently in situations where specially shaped bolts are needed.
Investigation on rotating compression of porous cylinder under constant shear friction using FEM simulation
Authors: Tzou Gow-Yi , Hwang Yeong-Maw , Pan Sai-Chih
Published: July 2018

In this paper, a series of systematic studies on the rotating compression of porous cylinders by the FEM using DEFORM-3D analysis software are carried out. For a series of simulations, the forming conditions such as (1) the angular velocities from small to large are 0, 0.1, 0.25, 0.5, and 1 (rad/sec), respectively;(2) aspect ratio of porous cylinder (height-diameter ratio) are 0.75, 1, and 1.25, respectively;(3) the frictional factors are 0.3 and 0.7. Through different combinations of the above-mentioned variation factors, the characteristics of the rotating compression of porous cylinder can be explored. These rotating forming characteristics such as the compression force, the bulging ratio, the change in density, the rotating torque and so on can be investigated. The rotating compression characteristics of both porous and sound cylinders reveal lots of similarities and some differences. The main conclusions of this study are as follows: (1) as the rotating speed increases fast, the compression force of porous cylinder is whereas reduced. This phenomenon is different from the compression of sound cylinder; (2)the compression force under the lower aspect ratio can be reduced by the lubrication; (3)the relative density can be increased by increasing the rotating speed and reduction ratio; (4)the rotating torque is increased with higher rotating speed, higher frictional factor, and higher aspect ratio; (5)the bulging effect can be reduced by increasing the rotating speed, however it is increased by increasing the frictional factor.
Fragmentierung des Fallmanagements in deutschen Krankenhausabteilungen
Authors: Holderried Martin , Wolpert Stephan , Zenner Hans-Peter , Maschmann Jens
Published: July 2018

Hintergrund Wesentliche Ziele von Krankenhäusern sind eine hohe Qualität, Sicherheit, Effektivität und Effizienz der Leistungserbringung. Dies erfordert
eine optimale Behandlungssteuerung durch das Fallmanagement auf den Krankenhausstationen (FM).

Methoden Für eine Analyse der Mikro- und Makroprozesse des stationären Fallmanagements wurde ein strukturiertes Interviewinventar entwickelt. Anschließend
wurde mit dem Interviewinventar eine Felduntersuchung als community based participatory research (CBPR) an homogenen Fokusgruppen von 24 deutschen, aus
ökonomischer Sicht als Profitcenter wirkenden, öffentlichen Krankenhausabteilungen der Maximalversorgung durchgeführt.

Ergebnisse Mit der CBPR-Feldstudie konnten 1.682 Mikroprozesse des stationären Fallmanagements der untersuchten Krankenhausabteilungen erfasst und
beurteilt werden. Die Studie zeigt, dass alle Abteilungen zwar ein umfangreiches klinisches Fallmanagement betreiben, die Mikroprozesse des Fallmanagements
allerdings durchgehend weder optimal zur Kostenminimierung noch maximal zur Liquiditäts-, Erlös- und Qualitätsverbesserung durchgeführt werden. Auch zeigt sich,
dass die berufsgruppenübergreifende Durchführung der Prozesse des FM durch Ärzte und Pflegekräfte mit einer erheblichen Fragmentierung des FM verbunden ist.

Schlussfolgerungen Die intensive Fragmentierung der Tätigkeiten des FM auf Krankenhausstationen legt die Erarbeitung von Strategien nahe, die Prozesse des
stationären Fallmanagements zu homogenisieren.
Toward a Catalytic Atroposelective Synthesis of Diaryl Ethers Through C(sp2)–H Alkylation with Nitroalkanes
Authors: Gustafson Jeffrey , Dinh Andrew , Noorbehesht Ryan , Toenjes Sean , Jackson Amy , Saputra Mirza , Maddox Sean
Published: July 2018

We report studies toward a small-molecule-catalytic approach to access atropisomeric diaryl ethers that proceeds through a C(sp2)–H alkylation using nitroalkanes as the alkyl source. A quaternary ammonium salt derived from quinine, containing a sterically hindered urea at the C-9 position, was found to effect atroposelective C(sp2)–H alkylation with moderate to good enantioselectivities across several naphthoquinone-containing diaryl ethers. Products could then be isolated in >95:5 er after one round of trituration. For several substrates that were evaluated, we obtained nitroethylated products in similar yields and selectivities.
A Novel Entry to 3,4,5-Trisubstituted 2-Pyrrolidones from Isoxazoline-N-oxides
Authors: Sukhorukov Alexey , Zhmurov Petr , Ushakov Pavel , Novikov Roman , Ioffe Sema
Published: July 2018

A novel strategy for the synthesis of stereochemically defined 3,4,5-trisubstituted 2-pyrrolidones was developed. The suggested approach involves reductive domino-type recyclization of 3-aminomethyl-substituted isoxazolines as a key stage. The latter are prepared via α-C–H functionalization of readily available isoxazoline-N-oxides.
Near-Peer Teaching Outreach Programs to Increase Minority Physician Recruitment
Authors: Linderman Wendy , Apostolopoulos Nicholas , Gopal Anand , Encandela John , Teng Christopher , Nwanyanwu Kristen , Forster Susan
Published: July 2018

Problem Health disparities among racial and ethnic groups exist in the United States despite improvements in health status and access to care. These inequalities may be reduced by increasing minority physician recruitment; however, how best to recruit these physicians remains unclear.

Approach Near-peer teachers are not professionally trained, but have recently learned material that they themselves teach. Near-peer teaching in minority student outreach programs may be effective in increasing minority physician recruitment. The authors used a near-peer teaching model to promote interest in medicine, specifically ophthalmology, as a potential career path for both volunteer near-peer teachers and minority high school students participating in an educational outreach program. Twenty-one college and graduate-school near-peer teachers of various racial and ethnic backgrounds participated to teach 31 inner-city high school students. The program was evaluated using pre- and posttest surveys assessing students' knowledge about and interest in science, medicine, and ophthalmology; analysis used pairwise t-test comparisons. Qualitative responses and an end-of-training survey also assessed students' and near-peer teachers' satisfaction with the program and perceptions about medicine as a career.

Outcomes Students' knowledge about and interest in medicine and ophthalmology increased significantly after participation. Near-peer teachers agreed that teaching in the program was beneficial to their careers and made it more likely that they would enter medicine and ophthalmology.

Next Steps The authors will track the near-peer teachers' career paths and, in the next iteration, will increase the number of program days. This intervention may serve as a model for outreach for other specialties beyond ophthalmology.
Paving the Path to Value: The Role of Registry Studies in Interventional Radiology
Authors: Wang Melinda , Kohi Maureen
Published: July 2018

The growth rate of interventional radiology (IR) procedures and practitioners has exceeded the pace of evidence development to support evidence-based practice. In the innovative and highly adaptive field of IR, there exists a tremendous need for interventional radiologists to practice evidence-based medicine as a way to maintain and improve quality of health care. Randomized controlled trials (RCTs) are considered to be the gold standard of research, providing level I evidence, but in procedural subspecialties, they remain difficult to design and implement due to challenges in randomization, blinding, and inadequate sample size. To build the foundation of evidence in IR, registry studies can play a complementary role to RCTs. Clinical data registries may offer a more practical approach to gathering outcomes data, important in this era with the advent of the Medicare Access and CHIP Reauthorization Act (MACRA), in comparison with RCTs. Properly designed registries can store an abundance of data with which high-quality observational studies can be performed. Although considered level II evidence, these registry studies will allow the evaluation of both performance and value of IR procedures, particularly in circumstances in which an RCT would not be feasible. This manuscript aims to serve as a guide for developing and participating in IR registry studies.
Osteophytic Iliac Venous Compression: Technical Considerations for a Bony May-Thurner Syndrome Variant
Authors: Shin David , Mokkarala Mahati , Allison Stephen , Monroe Eric
Published: July 2018

May-Thurner syndrome (MTS) results in compression of the left common iliac vein between the spine and right common iliac artery leading to symptomatic venous outflow obstruction. The authors depict a classic case of MTS followed by four variant cases in which the primary culprit lesions causing compression were degenerative vertebral osteophytes. The osteophytic variant of MTS poses distinct diagnostic and therapeutic challenges.
Classification of electroencephalogram signals using wavelet-CSP and projection extreme learning machine
Authors: Dai Yixuan , Zhang Xinman , Chen Zhiqi , Xu Xuebin
Published: July 2018

Brain-computer interface (BCI) systems establish a direct communication channel from the brain to an output device. As the basis of BCIs, recognizing motor imagery activities poses a considerable challenge to signal processing due to the complex and non-stationary characteristics. This paper introduces an optimal and intelligent method for motor imagery BCIs. Because of the robustness to noise, wavelet packet decomposition and common spatial pattern (CSP) methods were implemented to reduce the dimensions of preprocessed signals. And a novel and efficient classifier projection extreme learning machine (PELM) was employed to recognize the labels of electroencephalogram signals. Experiments have been performed on the BCI Competition Dataset to demonstrate the superiority of wavelet-CSP in BCI and the outperformance of the PELM-based method. Results show that the average recognition rate of PELM approaches approximately 70%, while the optimal rate of other methods is 72%, whose training time and classification time are relatively longer as 11.00 ms and 11.66 ms, respectively, compared with 4.75 ms and 4.87 ms obtained by using the proposed BCI system.
Nonlinear dynamics of river runoff elucidated by horizontal visibility graphs
Authors: Lange Holger , Sippel Sebastian , Rosso Osvaldo A.
Published: July 2018

Horizontal Visibility Graphs (HVGs) are a recently developed method to construct networks from time series. The values of the time series are considered as the nodes of the network and are linked to each other if there is no larger value between them, such as they can “see” each other. The network properties reflect the nonlinear dynamics of the time series. For some classes of stochastic processes and for periodic time series, analytical results can be obtained for network-derived quantities such as the degree distribution, the local clustering coefficient distribution, the mean path length, and others. HVGs have the potential to discern between deterministic-chaotic and correlated-stochastic time series. Here, we investigate the sensitivity of the HVG methodology to properties and pre-processing of real-world data, i.e., time series length, the presence of ties, and deseasonalization, using a set of around 150 runoff time series from managed rivers at daily resolution from Brazil with an average length of 65 years. We show that an application of HVGs on real-world time series requires a careful consideration of data pre-processing steps and analysis methodology before robust results and interpretations can be obtained. For example, one recent analysis of the degree distribution of runoff records reported pronounced sub-exponential “long-tailed” behavior of North American rivers, whereas another study of South American rivers showed hyper-exponential “short-tailed” behavior resembling correlated noise. We demonstrate, using the dataset of Brazilian rivers, that these apparently contradictory results can be reconciled by minor differences in data-preprocessing (here: small differences in subtracting the seasonal cycle). Hence, data-preprocessing that is conventional in hydrology (“deseasonalization”) changes long-term correlations and the overall runoff dynamics substantially, and we present empirical consequences and extensive simulations to investigate these issues from a HVG methodological perspective. After carefully accounting for these methodological aspects, the HVG analysis reveals that the river runoff dataset shows indeed complex behavior that appears to stem from a superposition of short-term correlated noise and “long-tailed behaviour,” i.e., highly connected nodes. Moreover, the construction of a dam along a river tends to increase short-term correlations in runoff series. In summary, the present study illustrates the (often substantial) effects of methodological and data-preprocessing choices for the interpretation of river runoff dynamics in the HVG framework and its general applicability for real-world time series.
Nonlinear hydrodynamic effects in dense microplasmas interacting with microwaves
Authors: Pederson Dylan M. , Kourtzanidis Konstantinos , Raja Laxminarayan L.
Published: July 2018

Plasmas respond nonlinearly to GHz electromagnetic waves, owing to nonlinear interactions described by the electron momentum equation. These nonlinearities are especially important in high field regions of the plasma as is common in resonant structures that generate plasma discharges with intense localized amplification of the incident field. Most models treat the plasma as a linear Drude material that does not capture the nonlinear polarization terms of a plasma. In this work, we couple the nonlinear electron momentum equation to electromagnetic wave simulation in order to explore the nonlinear behavior. We develop a theoretical foundation via perturbation analysis to guide our expectations from numerical simulation. Through numerical simulation of 2D TE-polarized waves incident on a cylindrical plasma, we show that in the presence of electrical field strengths of ∼MV/m and higher, dense microplasmas have second harmonic power conversion efficiency approaching 10−6 at low pressures. The generated harmonic power is shown to arise mostly from the inertial term in the electron momentum equation. Therefore, a significant portion of the harmonic current density is generated at the surfaces of critical electron density for the fundamental frequency.
Electron shock-surfing acceleration in the presence of magnetic field
Authors: Li R. , Zhou C. T. , Huang T. W. , Zhang H. , Qiao B. , Yu M. Y. , Ruan S. C. , He X. T.
Published: July 2018

The effect of perpendicular (to the direction of shock propagation) magnetic fields on electron shock-surfing acceleration (ESSA) is investigated. Two-dimensional particle-in-cell simulations show that the strength of background magnetic fields can significantly affect the shock formation process and the electrostatic field structure near the leading edge of the shock. It is found that ESSA is most efficient when the ratio of electron cyclotron frequency to plasma frequency is about 0.1. In this case, there are two types of electrostatic field structures near the shock edge, namely, small-scale filamentary and large-scale dipole electric fields, induced by the Buneman instability and fluid compression, respectively. In such a mixed field structure, the affected electrons can undergo multiple accelerations and gain much higher energies than that under weaker or stronger background magnetic fields.
Three dimensional analytical model of dipolarizing flux bundles
Authors: Beyene Fekireselassie , Artemyev Anton V. , Angelopoulos Vassilis , Vasko Ivan Y.
Published: July 2018

In many plasma systems, magnetic reconnection plays a crucial role in particle acceleration. In Earth's magnetotail, reconnection releases a significant portion of the stored magnetic energy (which is primarily converted into ion enthalpy) behind intense electromagnetic boundaries called dipolarization fronts. Dipolarizing flux bundles behind these fronts accelerate ambient plasma and transport charged particles from the magnetotail to near-Earth space. Appropriate modeling of such flux bundle-particle interactions requires self-consistent models that describe both the bundle's electromagnetic fields and the magnetotail's static background magnetic field. We develop a 2D solution of the Vlasov-Maxwell equation for a magnetotail with an embedded dipolarization front and generalize this solution to a 3D system. Our 3D model describes both global (within the magnetotail) and local (around the front) electromagnetic field distributions and a consistent distribution of plasma. The magnetic field topology in our model agrees with that deduced from multispacecraft observations. Our model can be used for a test particle tracing and investigation of particle acceleration/transport by dipolarization fronts in planetary magnetotails.
Interlayer strain effects on the structural behavior of BiFeO3/LaFeO3 superlattices
Authors: Carcan B. , Bouyanfif H. , El Marssi M. , Le Marrec F. , Dupont L. , Davoisne C. , Wolfman J. , Arnold D. C.
Published: July 2018

Artificial (BiFeO3)0.5Λ/(LaFeO3)0.5Λ superlattices have been grown by pulsed laser deposition. The periodicity Λ was varied from 150 Å to 25 Å and the relative ratio between BiFeO3 (BFO) and LaFeO3 (LFO) is kept constant in each period. X-ray diffraction, transmission electron microscopy, and Raman spectroscopy investigations indicate antiferroelectric-like structures for large periodicity (Λ ≥ 76 Å), while Pnma LaFeO3-like structures are observed for small periodicity Λ ≤ 50 Å. Room temperature magnetic measurements were obtained by vibrating sample magnetometry and suggest antiferromagnetic ordering with weak ferromagnetism. Temperature dependent x-ray diffraction studies show an important shift of paraelectric-antiferroelectric phase transition scaling with BFO thickness. Strain and size effects explain this behavior and discussion is also made on the possible role of the oxygen octahedral rotation/tilt degree of freedom.
Thermal transport properties of suspended graphene
Authors: Ma X. M. , Zou J. L. , Zhang J. F. , Guo C. C. , Liu K. , Wu F. , Xu W. , Zhang R. Y. , Zhu Z. H. , Qin S. Q.
Published: July 2018

Electrically biased graphene has been studied experimentally as a novel emitter of thermal radiation. However, there is as yet no systematic theory that quantifies the thermal radiation, heat transfer, and electrical properties of electrically biased graphene. To study the thermal transport properties systematically, a heat conduction model is developed and exploited in this paper. The temperature distribution and heat conduction coefficient of graphene under different bias voltages are obtained using our theoretical model. The I–V curve and the relationship between the radiant power and input voltage of graphene are then obtained. This work could help design a novel efficient wavelength-adjustable thermal radiation source.
Detailed analysis of transitions in the CO oxidation on palladium(111) under noisy conditions
Authors: Cisternas Jaime , Wehner Stefan
Published: July 2018

It has been shown that CO oxidation on Pd(111) under ultrahigh vacuum conditions can suffer rare transitions between two stable states triggered by weak intrinsic perturbations. Here we study the effects of adding controlled noise by varying the concentrations of O2 and CO that feed the vacuum chamber, while the total flux stays constant. In addition to the regime of rare transitions between states of different CO2 reaction rates induced by intrinsic fluctuations, we found three distinct effects of external noise depending on its strength: small noise suppresses transitions and stabilizes the upper rate state; medium noise induces bursting; and large noise gives rise to reversible transitions in both directions. To explain some of the features present in the dynamics, we propose an extended stochastic model that includes a global coupling through the gas phase to account for the removal of CO gas caused by the adsorption of the Pd surface. The numerical simulations based in the model show a qualitative agreement with the noise-induced transitions found in experiments, but suggest that more complex spatial phenomena are present in the observed fluctuations.
Generating low-temperature glow discharge plasma in the atmospheric pressure helium after spark breakdown: Modelling plasma with the prescribed properties for biomedical applications
Authors: Demkin V. P. , Melnichuk S. V. , Postnikov A. V.
Published: July 2018

This paper concerns computational modelling of the low-temperature glow discharge plasma in the atmospheric pressure helium after spark breakdown and research on the dependence of a spatial distribution of plasma on the initial conditions of discharge and parameters of the external electric circuit. This study analysed the influence of the initial distribution of a space charge on the generation of the glow discharge plasma after the spark breakdown between flat electrodes by means of a 2D-axial symmetric model of the atmospheric pressure helium plasma in the drift-diffusion approximation. With the discharge current of 1–12 mA, the solution for a quasi-steady state of plasma is obtained. The dependence of a type of this discharge mode on the parameters of the external electric circuit and coefficient of the secondary cathode emission is studied.
Quantitative measurements of non-covalent interactions with diamond based magnetic imaging
Authors: Kayci Metin , Lourette Sean , Wang Tao , Bougas Lykourgos , Budker Dmitry
Published: July 2018

We present a technique employing dielectrophoretic (DEP) manipulation of surface immobilized complexes integrated with a magnetic imaging platform based on nitrogen-vacancy (NV) centers in diamond for the quantitative measurements of non-covalent interactions. The interdigitated microelectrodes closely spaced to the functionalized surface of the diamond plate provide a wide range of applied DEP forces for noninvasive manipulation of various molecular interactions, while the NV layer under the surface reports the unbinding dynamics. Given that biological samples do not present significant magnetic background and do not screen magnetic fields, our approach has many advantages over the fluorescent tagging where the optical signal is subject to photo-bleaching, auto-fluorescence, and instabilities. The high sensitivity and spatial resolution provided by NV-based magnetic imaging make this technique a useful tool for biophysical applications.