bluuebunny/crossref_metadata_2025_split huggingface dataset:
Competencias, objetivos, habilidades y destrezas: ¿cómo entender las diferencias conceptuales? Una analogía de entendimiento a partir de un bloqueo en el tránsito automotor
Authors: Amaya A. Adalberto 
Published: December 2019

Uno de los grandes problemas que enfrentan los docentes, a partir de la revolución educativa curricular centrada en competencias, corresponde a la adaptación del término competencia, que viene del lenguaje laboral, y entenderlo desde el lenguaje académico aplicándolo, además, a las carreras profesionales. Se considera, por lo tanto, necesario aclarar el concepto desde un punto de vista académico y profesional, para analizar los elementos que caracterizan la distinción del término competencia y su diferenciación con las tendencias curriculares precedentes centradas en objetivos y contenidos temáticos. Si bien es cierto que inicialmente se analiza el inconveniente gramatical que ha favorecido la confusión de términos, posteriormente, a través de una estrategia didáctica, se genera un análisis respecto a las diferencias entre competencias, habilidades y destrezas, a partir de una analogía que se hace con un ejemplo de un bloqueo en el tránsito automotor.
Lesiones cutáneas en pacientes con trasplante renal en el Hospital Universitario San Ignacio
Authors: Cuéllar Isabel , Rodríguez Edna , García Paola , Hernández Carolina , Pinto Ramírez Jessica Liliana 
Published: December 2019

Introducción: Las enfermedades cutáneas son frecuentes en los pacientes trasplantados renales, por lo cual el monitoreo de la piel es necesario para realizar un diagnóstico precoz e iniciar tratamiento temprano.Objetivo: Determinar la prevalencia de las manifestaciones cutáneas en pacientes con trasplante renal. Materiales y métodos: Se evaluaron en consulta de dermatología 86 pacientes del programa de trasplante renal del Hospital Universitario San Ignacio.Resultados: Las infecciones de piel fueron las manifestaciones más prevalentes, y dentro de estas las más frecuentes fueron las micosis superficiales presentes, en un 48 % de los pacientes; seguidas por las infecciones virales, en un 20 %, y las bacterianas, en un 15 %. Se encontraron dos casos de cáncer de piel: un carcinoma basocelular y un sarcoma de Kaposi. Doce pacientes tuvieron queratosis actínicas consideradas lesiones premalignas.Conclusión: Los resultados del estudio evidencian la necesidad de realizar un examen dermatológico rutinario en los pacientes trasplantados para detectar tempranamente la presencia de lesiones cutáneas y, de esta manera, iniciar un manejo oportuno. Los hallazgos más comunes fueron las micosis superficiales.
Neuromielitis óptica en el embarazo: reporte de un caso
Authors: Laurens Acevedo Michelle , Castañeda C. Camilo , Ruiz de Sánchez Carolina , Rueda María Camila , Zarco M. Luis Alfonso 
Published: December 2019

La neuromielitis óptica (NMO) es una enfermedad inflamatoria autoinmune desmielinizante del sistema nervioso central, mediada por autoanticuerpos contra el receptor de acuaporina 4 (Ac IgQ4). Se presenta el caso de una mujer de 23 años de edad con 28 semanas de embarazo y antecedente de neuromielitis óptica, quien consultó por recaída de la enfermedad y pobre respuesta al manejo con corticosteroides, por lo que recibió 5 sesiones de plasmaféresis y tuvo una importante mejoría clínica.
Molecular Dynamics Study on Microscopic Mechanism of Dissolution, Diffusion and Aggregation Process for Waxy Molecules in the Process of Waxy Crude Oil Pipeline Transportation
Authors: Gan Yifan , Cheng Qinglin , Wang Zhihua , Yang Jinwei , Sun Wei , Liu Yang 
Published: December 2019

Abstract

In order to ensure the safe and economic operation of waxy crude oil transportation process, the micro-dynamic mechanism and thermodynamic characteristics of wax precipitation process at nanoscale are necessary to be revealed. Here, we established the molecular dynamics model to characterize the phase transition and precipitation behavior of waxy molecules in multiphase system (including oil, asphaltene and water), the relative error between simulated results and experimental data measured by Dutour et al. (2002) is less than 5%. Under the coupling effect of different operation parameters, the molecular dynamics simulation was employed, the simulated results showed that the spherical paraffin crystals underwent the process of dissolution, diffusion and aggregation, then the waxy cluster crystals with larger amount but smaller volume would form, and it would deposit on the outer wall under the concentration gradient. The influence mechanism of different operating parameters on wax precipitation was analyzed, of which the increase of temperature and water cut will decrease the wax precipitation, while the increase of pressure will enhance the wax precipitation rate, furthermore, by means of the hydrogen bonding and the effect of similar dissolution, the water and asphaltene molecules also affect the wax precipitation process at molecular-scale. The researches of this paper provide the theoretical support for the paraffin removal and control in waxy crude oil pipeline transportation process.
The Comparison and Parameters Optimization for the Mixed Intermediate Fluid of Intermediate Fluid Vaporizer
Authors: Yan Yan , Li Yuxing , Wang Shuo 
Published: December 2019

Abstract
In this paper, an establishment of heat transfer model is performed to study the effects of different types of mixed intermediate fluid on the vaporizer performance. It is found that compared with pure propane, mixed ethane-propane working fluid can bring about a reduction of 10% ∼ 25% for the heat exchange area of intermediate fluid vaporizer IFV. In addition, using mixed butane-propane working medium could stabilize the saturated pressure of intermediate fluid at a relatively low level of 0.2 MPa, while the saturated pressure of pure propane ranges from 0.33 MPa to 0.65 MPa. Thereby, the former one is more reliable than the latter one in an aspect of safe operation. Moreover, after an investigation and selection, the results show that the saturated pressure of intermediate fluid varying from 0.3 MPa to 0.6 MPa and the amount of LNG overloaded over than 130% is beneficial for the improvement of comprehensive heat transfer performance of IFV.
Numerical Simulation of Multi-Phase Flow Distribution in Parallel Pipelines System of Oil Transfer Station
Authors: Wang Yingying , Wang Chunsheng , Sun Qiji , Lv Yuling 
Published: December 2019

Abstract
The mal-distribution of gas-oil-water multi-phase flow in parallel petroleum processing pipelines can directly affect the working condition of the separators. In this paper, the influence of different factors on the flow distribution and the characteristics of gas-oil-water distribution in parallel pipelines was investigated by three-dimensional CFD numerical simulation. Firstly, four different simulation models are established based on different arrangement types of parallel pipelines. The simulation results show that the distribution of gas-oil-water flow in the radial entry symmetrical two-stage pipe-laying simulation model was the most uniform among the four simulation models. Then, four radial entry symmetrical two-stage pipe-laying simulation models with different distance between branch pipes were establish. From the simulated results, it can be found that the distance has no effect on the distribution of gas-oil-water flow in each branch pipe, but great influence on distribution of flow rate in each branch pipe. Finally, the influence of the inlet flow characters on the flow distribution is investigated. It can be found that the “bias flow” phenomenon of the parallel pipelines decreasing with the increase of the inlet flow velocity, the gas content of inlet flow and the water content of inlet liquid.
Analysis on Optimized Operation of Trans-Asia Gas Pipeline
Authors: Jinwei Yang , Qinglin Cheng , Yifan Gan , Yanxin Ma , Yun Feng , Yi Ding 
Published: December 2019

Abstract
In order to ensure efficiency of Trans-Asia Gas Pipeline, engineers in Sino-Petroleum International Company optimized pipeline operation from a whole view through simulated optimization and unit control optimization. The network model of ABC line is established using TGNET, and the error of model is adjusted to the acceptable range by using the practical data. Flow distribution of AB line and C line is optimized to ensure the minimum fuel cost. Principle of gas pack control is built in different working conditions. And the compressor unit is controlled according to the simulation results. Performance of compressor unit is monitored and control mode is regulated to a better way on the basis of data analysis and investigation. After more than one year of exploration and practice, the operation optimization methodology of the Trans-Asia Gas Pipeline has been established. Energy-saving effect is remarkable.
Research on Methods to Solve Emulsion Phenomenon in the Transportation of Diesel Through Pipeline
Authors: Li Wang , Huang Liqiao 
Published: December 2019

Abstract
This paper describes and analyzes the emulsion phenomenon of diesel in commissioning of Products Pipeline by Sinopec and PetroChina in recent years. Studies have shown that the ester anti-wear agent in diesel oil as well as the interface active substance contained in diesel are the emulsifiers of diesel and water, which cause the emulsification of diesel and water under strong shearing in pipeline. On the basis of this background, isentropic simulation experiment is carried out to obtain the emulsion in laboratory by creating a similar shearing stress. The basic properties of diesel, anti-wear properties and emulsion stability are studied, and the rate of water content, surface tension and droplet size are compared and analyzed. Then based on oil-water separation experiment, solutions to diesel emulsification, relevant experience and suggestions for the production of refined oil pipelines are put forward, which may be valuable reference for future commission of Products Pipeline.
Measuring the Losses of Hydrostatic Pumps and Motors: A Critical Review of ISO4409:2007
Authors: Achten Peter , Mommers Robin , Nishiumi Takao , Murrenhoff Hubertus , Sepehri Nariman , Stelson Kim , Palmberg Jan-Ove , Schmitz Katharina 
Published: December 2019

Abstract
ISO 4409 is the most important international standard for measuring the efficiency of hydraulic pumps and motors, the latest edition being 4409:2007. The standard describes methods for determining the steady-state performance in terms of overall efficiency. It also defines equations for calculating the volumetric efficiency of pumps and motors. The hydro-mechanical efficiency is only defined for motors, not for pumps.
This paper analyses the efficiency and losses of pumps and motors in an alternative way. The preference is on loss analysis instead of efficiencies. Especially the effects of the bulk modulus are considered in a different and more inclusive manner. The new methodology results in a higher total loss for motor and a lower total loss for pumps than the current ISO 4409 standard. Furthermore, it results in significant changes of the hydro-mechanical and volumetric losses. The differences between the new methodology and ISO 4409 become larger for high load pressures.
The new methodology demands knowledge about the minimum volume of the displacement chamber. The ratio between this volume and the full displacement of a single displacement chamber strongly influences the hydro-mechanical and volumetric losses of the pump or motor. The new methodology is valid for all positive displacement hydrostatic pumps and motors. The volumetric efficiency, as defined in ISO 4409, can still be used as a flow rate factor, but should not be regarded as an energy conversion efficiency.
The importance of adopting the proposed methodology is further demonstrated by analyzing and comparing the measurement data about a fixed displacement pump and motor, showing the differences in the loss analysis by means of ISO 4409 and the new equations.
The methodology, observations and validation results presented in this paper are significant and can pave the road for improving the current ISO 4409:2007 standard, which would ultimately benefit the industry.
Intelligent Machine Operator Identification to Develop Damage-Reducing Operating Strategies for Mobile Machines
Authors: Brinkschulte Lars , Geimer Marcus 
Published: December 2019

Abstract
Mobile machines are exposed to a multitude of influencing factors, such as the working task, the operator and the environmental conditions. This leads to a broad spectrum of load collectives for the machine components. In many cases it is difficult to influence the working task and the environmental conditions under the objective function of achieving the required work goals optimally while at the same time minimizing the component load. The operation of the machine offers a more evident degree of freedom to minimize the component damage. With control systems adapted to the operator, the external environmental conditions and the working task, which instructs the operator to a less damaging operating behaviour or override the damage-initiating control signals, the loads and damage can be reduced. An explicit operator identification is the basis for such control approaches.
This paper presents a method for machine operator identification (MOI) based on Hidden Markov Models (HMM). Through a parameter influence analysis and a combination with operation state recognition (OSR), a machine operator can be successfully identified among others. To create and validate the method, measurement data from 150 work cycles of seven different operators are analysed. Based on the MOI, a method for an operator-specific damage reduction using adaptive control strategies is developed. The results and limits of this strategy are presented and discussed by means of a complete machine simulation, considering the traction drive and function drives (working hydraulics), a multi-body simulation and the driving dynamics. The conclusion is made by considering predictive operating strategies to avoid damage-intensive operating points.
Novel Pressure Adaptive Piston Cylinder Interface Design for Axial Piston Machines
Authors: Sarode Shanmukh , Shang Lizhi 
Published: December 2019

Abstract
The paper presents a novel concept of a pressure adaptive piston/cylinder interface design for a swashplate type axial piston machine that uses a pressurized groove around the bushing inside the cylinder block. This groove is connected to the pump displacement chamber and it uses pressure deformations of the bushing to improve the sealing function of the piston/cylinder lubricating interface. Such a design concept is based on a groove design that is easy to manufacture, thus resulting in a cost-effective design solution.
The proposed piston/cylinder interface design is simulated using a multi-domain simulation model developed by the authors’ research team. The tool is particularly suitable for the analysis of the internal gap flows, being based on a fully coupled fluid structure thermal interaction model, which calculates the non-isothermal gap fluid behavior considering solid body deformations due to temperature and pressure effects.
The proposed solution is compared in simulation with respect to a standard design of an axial piston pump. The results indicate that the proposed pressure adaptive piston/cylinder interface is able to improve the sealing function of the piston/cylinder interface at different operating conditions. Therefore, the proposed novel design can be seen as a possible method to increase the energy efficiency of the current designs of swash plate units.
Switch-Mode Power Transformer in a Wave-Powered, Reverse Osmosis Desalination Plant
Authors: Simmons Jeremy W. , Van de Ven James D. 
Published: December 2019

Abstract
In the reverse osmosis (RO) desalination process, a salt water solution is pressurized to overcome the osmotic pressure across a semi-permeable membrane. A few groups have proposed that a wave energy converter (WEC) having a seawater based, hydraulic power take-off can could be used to pressurize the feedwater for an RO system. However, coupling the wave energy harvesting process and the RO desalination process imposes unique design constraints on the fluid power system, such as pressure limits of conventional RO system components. In this study, a fluid power circuit with a switch-mode power transformer is used to transfer power while keeping the pressure of the power take-off and RO processes relatively decoupled. The switch-mode power transformer studied herein adds fewer costly components and less significant loss mechanisms to the system than a conventional hydraulic transformer performing the same function. The switch-mode power transformer uses the inertia of a hydraulic motor driven electric generator and switching of the hydraulic motor inlet between high and low-pressure sources to decrease the pressure at which power is being transmitted to the RO process. This process is analogous to DC-DC switching power transformers in the electrical domain. This study seeks to demonstrate this unique switch-mode system as a potential solution for coupling the wave-energy harvesting process with the reverse osmosis process. The system is modeled and studied in the context that the transformer and RO system are onshore, 500 meters from the WEC. Power captured from the WEC is transmitted through a long pipeline to shore. A distributed parameter model is used to model the pipeline dynamics, simultaneously revealing the significance of these dynamics and the robustness with which the switch-mode transformer decouples the pressure dynamics at the RO feed from the pipeline dynamics. The switch-mode power transformer is estimated to be 76% efficient while the system, as a whole, is estimated to be 45% efficient.
Theoretical Modeling, Analysis, and Experimental Results of a Hydraulic Artificial Muscle Prototype
Authors: Slightam Jonathon E. , Nagurka Mark L. 
Published: December 2019

Abstract
Fluidic braided artificial muscles have been studied for close to seventy years. Their high power-to-weight ratio and force-to-weight ratio make them a desirable actuation technology for compact and lightweight mobile manipulation. Use of hydraulics with fluidic artificial muscles has helped realize high actuation forces with new potential applications. To achieve large actuation forces produced from high internal pressure, artificial muscles operate near the limitations of their mechanical strength. Design improvements and future applications in mechanical systems will benefit from detailed theoretical analysis of the fluidic artificial muscle mechanics. This paper presents the theoretical modeling of a hydraulic artificial muscle, analysis of its mechanics, and experimental results that validate the model. A prototype is analyzed that operates at 14 MPa and can generate up to 6.3 kN of force and a displacement of 21.5 mm. This model promises to be useful for mechanical system design and model-based control.
Energetically Passive Bilateral Teleoperation of a Pneumatic Crawling Robot
Authors: Durbha Venkat , Li Perry Y. 
Published: December 2019

Abstract
This paper presents the control methodology and experimental results for the bilateral haptic tele-operation of a pneumatic actuated crawling robot. The two front legs of a robot are teleoperated via a pair of PHANToM haptic interfaces. The system gives the human operator the impression that he/she is physically moving and positioning the robot legs. As the legs hit the ground, the operator would also feel the reaction force via the haptic feedback provided by the PHANToMs. To reduce the physical effort by the operator, kinematic and power scaling factors are applied. For stable tele-operation, the closed loop system is controlled to behave like a common energetically passive mechanical tool interacting with the human operator (on the PHANToM’s end) and the physical environment (on the Crawler’s end). The control design strategy treats the pneumatic actuators as a two-port nonlinear spring. While the mechanical port of the actuator acts on the mechanical structure of the crawler’s leg, the fluid port of the actuator is controlled to mimic the interaction between the pneumatic spring and the PHANToM, and to achieve co-ordination. The control methodology has been tested experimentally. While performing crawling motion, the RMS error of the robot foot placement error was 7mm, well within the crawler’s foot diameter of 25.4mm.
Stirling Thermocompressor: Lumped Parameter Modeling and Experimental Impact of Displacer Motion Profile on Work Output
Authors: Thomas Seth , Barth Eric J. 
Published: December 2019

Abstract
The thermocompressor, a little-known class of Stirling devices that efficiently compresses gas, presents new challenges for modeling and experimental validation. In modeling, traditional analytic assumptions about displacer motion are limiting. In experimental verification, few devices have actually been built and tested. In this paper, the authors test the feasibility of a lumped-parameter approach for predicting the performance of Stirling thermocompressors subject to different displacer motion profiles. Since the displacer of a thermocompressor can be controlled independently, unlike kinematic Stirling engines or dynamic Stirling engines, and has a large influence on output power and efficiency of the device, it is crucial that this is well captured by a system dynamics model for control. Key model parameters are simulated and results are experimentally verified on one of the few, if only, experimental thermocompressor platforms in the world. Conclusions are drawn regarding simplified modeling of the regenerator’s effectiveness and the effects on device work output by varying the displacer piston’s motion profile using different waveforms.
Power Optimization of Series Hydraulic Hybrid Powertrain for Compact Wheel Loader
Authors: Wen Qunya , Wang Feng , Xu Bing , Sun Zongxuan 
Published: December 2019

Abstract
As an effective approach to improving the fuel economy of heavy duty vehicles, hydraulic hybrid has shown great potentials in off-road applications. Although the fuel economy improvement is achieved through different hybrid architectures (parallel, series and power split), the energy management strategy is still the key to hydraulic hybrid powertrain. Different optimization methods provide powerful tools for energy management strategy of hybrid powertrain. In this paper a power optimization method based on equivalent consumption minimization strategy has been proposed for a series hydraulic hybrid wheel loader. To show the fuel saving potential of the proposed strategy, the fuel consumption of the hydraulic hybrid wheel loader with equivalent consumption minimization strategy was investigated and compared with the system with a rule-based strategy. The parameter study of the equivalent consumption minimization strategy has also been conducted.