Technical Evaluations Research Articles

Research and Development of Supercritical Carbon Dioxide Coal-Fired Power Systems

Using supercritical carbon dioxide (S-CO2) Brayton cycle instead of the traditional steam Rankine cycle is a promising technique to enhance the coal-fired power generation efficiency. Researchers from all over the world are actively designing and exploring efficient S-CO2 coal-fired power plants in recent years with great efforts made to overcome the significant technical challenges in the cycle layouts of S-CO2 and its specific thermal integration with coal-fired heat resources. This paper provides a detailed review of the research progress on the coal-fired power generation using S-CO2 Brayton cycles. The basic knowledge of S-CO2 properties, the promising S-CO2 power cycles and the conceptual designs for S-CO2 coal-fired power plants are comprehensively summarized, with some key issues in the constructing process and the corresponding engineering solutions being emphatically discussed. Based on the current achievements, the overall technical and economic evaluations on the S-CO2 coal-fired power system are figured out. Furthermore, the specific integration applications of S-CO2 cycles with different coal firing devices and modes including pulverized coal combustion, circulating fluidized bed combustion, oxy-coal combustion, pressurized fluidized bed combustion, chemical looping combustion are discussed. Finally, the main challenges requiring further studies are highlighted.

Brief report on combat trauma surgical training using a perfused cadaver model.

Surgical combat casualty care presents difficult training challenges. Although several high-fidelity simulation (SIM) techniques have emerged, none are able to fully integrate the many intricacies involved in the care of a complex trauma patient. Herein, we report the use of perfused fresh human cadaver model for training and assessment of forward surgical teams (FSTs). Forward surgical teams attend a 4-day combat trauma surgical skills course including focused on trauma exposures. A half-day SIM involves the entire surgical team in four sequential surgical scenarios that involve the neck, chest, abdomen, and extremities, as well as airway management and resuscitation. Teams undergo immediate debriefing and videotape review of team dynamics and technical skills, as well as times to completion of critical interventions. The data evaluated include five initial demonstration courses in which training metrics were available. Each team included both a junior and experienced surgeon, anesthesiologists, and surgical scrub technicians. As FSTs progressed through SIMs, they demonstrated improvements in team dynamics and technical skills evaluations. There was considerable variability in the times to completion of critical intervention, particularly for control of cardiac and vascular injuries. Initial evaluations support the use of this novel perfused cadaver model for the training and evaluation of military FSTs. Preliminary data highlight the utility for open vascular, thoracic, and other high-acuity/low-volume procedures critical to combat casualty care. Larger studies are needed for model optimization and further validation of an objective structured technical assessment tool. Care management, level V.

Preparing Track Geometry Data for Automated Maintenance Planning

Research on track quality behavior has been extensively published, and many different approaches have been presented to describe the process of track quality. The research goal of this paper is to form a basis for a data-driven tamping prediction based on track quality analyses over time. A research database containing asset information, executed maintenance tasks, and measuring data of some 4,400 km of track of the Austrian rail network in a time sequence of 16 years is available. The modified standard deviation of vertical track geometry is identified as an ideal track quality indicator for planning and predicting tamping tasks in Austria in the context of this research. Further analyses show that a linear regression function is best suited for describing track quality between two tamping tasks and shows the best accuracy for predicting track quality in the future. An algorithm was developed by means of the linear regression function that enables analyses of track quality behavior over time for long time series and the whole network. This includes track quality before and after tamping tasks as well as deterioration rates. In the future, these basics have to be combined with further technical evaluations to detect an optimal intervention limit. Furthermore, economical and operational considerations must be incorporated to find the optimal tamping strategy under the given conditions.

Inter-Basin Water Diversion Projects and Inland Waterways: The Case of the Eurasian Grasslands

By employing the method of GIS spatial analysis, this paper plans and designs nine inter-basin water diversion projects and a Euro-Asia Canal system for the Eurasian Grasslands. The technical feasibility is analyzed for the key engineering projects. Technical and economic evaluations are calculated for nine water diversion projects. The multiple indirect benefits of these water diversion project and the canal system are elaborated. Main conclusions are that the water diversion and canal system projects are feasible; the economic benefits of the project are obvious; they can greatly promote economic development of countries along the ancient Silk Road.

Evaluation of the Two-Stage Fermentative Hydrogen Production from Sugar Beet Molasses

Fermentative hydrogen production from molasses—a renewable by-product of beet-sugar processing—was considered. Technical and economic evaluations were performed of a stand-alone production plant employing a two-step fermentation process (dark thermophilic fermentation and photofermentation) followed by an adsorption-based upgrading of the produced hydrogen gas. Using a state-of-the-art knowledge base and a mathematical model composed of mass and energy balances, as well as economic relationships, the process was simulated and equipment data were estimated, the hydrogen cost was calculated and a sensibility analysis was carried out. Due to high capital, operating and labor costs, hydrogen production cost was estimated at a rather high level of 32.68 EUR/kg, while the energy output in produced hydrogen was determined as 68% more than the combined input of the thermal and electric energy needed for plant operation. As the room for improvement of plant performance is limited, a perspective on the cost competitiveness of large-scale hydrogen production from fossil sources is unclear.

Analysis and Improvement Suggestions on Change of Medical Devices Licensing Items

Based on the statistics of 350 technical evaluations of changes in licensing items of class Ⅱ passive and active medical devices completed in Henan province from July 2017 to November 2018, this paper summarized and analysed the common problems and requirements listed in the correction notifications of the technical evaluation, and put forward relevant countermeasures or suggestions, with a view to further speeding up the evaluation and approval of medical devices.

On the Marine Energy Resources of Mexico

The Atlantic and Pacific coasts of Mexico offer a variety of marine energy sources for exploitation. Although the Mexican government has made important efforts to reduce its dependence on fossil fuels, national participation in clean energies is still limited in terms of electricity production. This paper presents a practical theoretical assessment of marine energy sources around Mexico, with the aim of identifying potential zones for subsequent, more detailed, technical evaluations and project implementations. The energy sources considered are ocean currents, waves, salinity, and thermal gradients. Using global databases, the percentages of energy availability for the defined thresholds were computed to establish the prospective regions with the most persistent power availability. This approach proved to offer more meaningful information than simple averaged values. Moreover, some environmental and socio-economic factors to be considered for future ocean energy resource assessments in Mexico were also discussed. The results show that the wave energy potential is highest in the northwest of Mexico (~2–10 kW/m for more than 50% of the time), and that there is a constant source of ocean current energy off Quintana Roo state (~32–215 W/m2 for more than 50% of the time). The thermal gradient power is more persistent in the southwest and southeast of the country, where ~100–200 MW can be found 70% of the time. The salinity gradient energy is strongest in the southeast of Mexico. The practical approach presented here can be extended to perform preliminary resources assessments in regions where information is scarce.

Nuclear Forensics and Development of Non-Destructive Scrutiny Facility (NDSF) for the Kingdom of Saudi Arabia

In this paper, theoretical model for nuclear forensics is developed and the Kingdom of Saudi Arabia (KSA) is considered as the case study. The main objective of this research is the development of procedure for nuclear forensics and infrastructure for non-destructive scrutiny facility (NDSF). In this study, various assumptions and parameters were discussed including the development strategies, technical evaluations, capabilities and current scenarios. The prime objective is to gain insight to the threat and unexpected issues regarding the race of nuclear technology in Middle East and North Africa (MENA) region and to safer the KSA region.

Experimental and numerical assessment of a methodology for performance prediction of Pumps-as-Turbines (PaTs) operating in off-design conditions

In this work, an extensive assessment of a predicting model used to evaluate Pumps-as-Turbines’ (PaTs) characteristic curves is presented, with specific attention to the off-design operating conditions. The novelty of the proposed model consists in the possibility to reconstruct the performance curves of a PaT only by knowing a limited number of operating data in turbine mode at the Best Efficiency Point (BEP), which, in many applications, represents a design constraint. The availability of the off-design performance curves supplies important indications for technical and economic evaluations in those applications where a constant flow rate cannot be granted. The predicting model was derived by re-elaborating a wide experimental data-set based on the most relevant scientific literature related to several PaTs operating in turbine mode. The prediction’s capability of the model was validated with experimental tests and confirmed by numerical simulations. The experimental tests were carried on in both direct and reverse modes by inspecting several flow rates. The model data were compared with the experimental ones in order to validate the Computational Fluid Dynamics (CFD) analyses. Subsequently, the numerical model was used to investigate the performances of other two PaTs operating in turbine mode. The study of the performance obtained with the CFD analyses allowed to evaluate the effectiveness of the predicting model, highlighting its pros together with its possible improvements. In general, it is possible to conclude that the proposed model is able to predict the performances of the studied PaTs with errors included in the range of ±7% with respect to the Best Efficiency Point (BEP) in turbine mode.

Moving for Cures: Breast Cancer and Mobility in Italy

ABSTRACTI combine the theoretical tools of medical anthropology and the framework of mobility studies to explore the intranational movements of women with breast cancer from Southern and Northern Italy. Differences include patients’ technical and moral evaluations of doctors, that influence the patients’ definitions of cure and illness experiences through their mobility and immobility. These (im)mobilities are, in turn, linked to the material and symbolic inequalities between Southern and Northern Italy and to the stigma attached to the south. These (im)mobilities suggest the need to further articulate the concept of cure.

Nanoindentation and Bending Fracture Behavior of Flexible Sulfide Thin Films Grown at Near Room Temperature With in Situ Tensile/Compressive Stress

Residual stress is known to affect significantly the mechanical fracture behavior of flexible thin films. Here, an in situ chemical deposition process that allows for control of extra compressive or tensile stress in PbS thin films is suggested. This process uses the fixed convex or concave surface of a flexible substrate to impart compressive or tensile stress, respectively, after the releasing step to the flat mode. Using two technical evaluations of mechanical fracture behavior, the existence of extra stress is verified with expected enhancements of the fracture resistance only in the case of compressive stress. For example, a ≈36% improvement of the elastic modulus is confirmed by nanoindentation testing for compressively stressed PbS thin films. The bending fracture resistance is also enhanced for the compressively stressed films, as evidenced by a ≈18.5% improvement in the crack‐initiating critical strain and a ≈121% increment in the fracture energy under the bending motion.

A methodical approach for improved control of safety-related product properties in early phases of the automotive product development process

Pedestrians are among the most vulnerable participants in current urban traffic. For this reason, the legal requirements for vehicle-related pedestrian protection are becoming increasingly stringent, which requires the development of more effective protection concepts. The development of constructive and technological traffic safety measures usually takes place within the framework of a company-specific product development process, which is divided into different phases. Many fundamental considerations regarding the design of the vehicle take place primarily in phases such as product planning or automotive design process (in the sense of the creative vehicle shaping process), which permit few detailed and resilient technical evaluations. Using the example of the automotive design process, an approach for a procedure model is presented that is intended to support the evaluation of safety-relevant product properties in the early phases of product development. The main components are on the one hand the structured analysis and classification of product models with regard to their technical evaluability. On the other hand, in order to support the safety-related development process to be mastered by integrating suitable tools, the basic procedure for the subsequent targeted adaptation of design methods is described.

Thermo-Physical and Mechanical Properties of Al Hashimiyya Basaltic Rocks, Jordan

Geothermal exploration in northern Jordan is in juvenile phase. North eastern basaltic desert is expected to host, with other rock formations, a shallow geothermal field. For efficient geothermal potential evaluation, a complete understanding of thermo-physical properties of deep reservoir rocks is of utmost importance. Due to the complex technical thermo-physical evaluations of basalts in depth, surficial basalts extending to the west were evaluated. Accordingly, six basaltic sub-flows from Al Hashimiyya were examined into their thermo-physical and mechanical properties. The flows represent the western extinction of large olivine basalt eruption. Different properties were evaluated for oven dried samples: thermal conductivity, permeability, porosity, density and specific heat capacity. In addition, basalts mechanical properties were examined: compressional wave velocity, unconfined compressive strength, indirect tensile strength and point load tests. The results were correlated in proportional patterns. They indicated that thermal conductivity of the studied basalts is dependent on porosity and permeability in parallel with mineral composition. It’s found that mechanical properties are controlled by porosity and permeability, too. The studied basalt properties exhibit slight deviation from the continental basalts thermo-physical and mechanical properties reported in the region. Thermal conductivity ranges between 1.89 and 1.32 W·m-1·K-1, whereas the porosity and permeability averages at 10.64% and 9.75899E-15 m2, respectively. Additionally, unconfined compressive strength averages at 104.9 Mpa and it’s almost 20 times higher than indirect tensile strength which ranges from 8.73 to 2.21 Mpa. As the samples were tested under laboratory conditions, in situ conditions will not be reflected by such values. At greater depth, temperature, pressure and hydrothermal activities will certainly affect rock properties. Micro fractures, whether it will be filled or not, will affect basalts properties, too. The results of this work will be used to develop a comprehensive thermo-physico-mechanical model, and improve the ability to predict rock properties at greater depths of Jordanian basalts.

Knowledge Politics in Environmental Conflicts: A Case from Brazil

Following large environmental conflicts and disasters, economic endeavors -particular large-scale investments in mining or hydropower- are nowadays subjected to rigorous environmental law and regulations. The application of rules and regulations takes place in environmental administration and courts and includes environmental impact assessments (EIAs, and does not correspond to the identical English acronym), licensing processes and litigation in court. Within these contexts, decision making is supposed to be based on rational reasoning and purportedly impartial scientific knowledge and information. Thus, citizens’ rights in resource conflicts and the effective enforcement of these rights in administrative, judicial, and political contestation become highly dependent on knowledge and information and the ways it is produced, interpreted, and valued in the interaction between people affected and investors, lays and experts, bureaucrats, legal practitioners and citizens. Political contestation becomes seemingly a technical dispute. This paper bases on a qualitative study of the conflicts surrounding the establishment of the large-scale iron-ore mining project Minas-Rio, in Conceição do Mato Dentro, Minas Gerais, Brazil, conducted in 2014-2015. It describes the problematic nature of the production of information and knowledge in a given political-economic context and the contestations surrounding the validity of apparently scientific results as they emerged alongside the environmental licensing process. Environmental studies and their technical evaluations are based on questionable assumptions and often lack accurate baseline data. The deficiency of public resources for independent investigation makes the environmental agencies dependent on services and information provided by mining companies. Apart from this form of collaboration, the prioritization of allegedly scientific “expert” knowledge, career trajectories of agencies’ personnel, and pressure by pro-mining politicians leads to the uncritical adoption of data, information and knowledge provided by the company and/or the consultancy firms employed by them. At the same time, information given by the people affected and environmentalists becomes sidelined. Thereby, the basic environmental and citizen rights, as the rights to information concerning the environment and to participation in licensing processes, guaranteed in the Brazilian constitution and environmental legislation, become ineffective.

Evaluation of Metro Kapsul Performance in Steady State Curving, Traction, and Braking

Transportation is an important life aspect to save travel time from one place to another. However, traffic congestion is a major problem. Therefore, PT TReKKa intends to develop Metro Kapsul, a mass public transportation system that is suitable for densely populated developed cities. A series of technical analyses and evaluations is necessary to ensure vehicle safety in steady-state curving, traction, and braking. The maximum velocity and acceleration/deceleration in these conditions can be used to decide the development and manufacturing process of Metro Kapsul. The analyses consisted of theoretical and numerical simulations. The theoretical analysis involved applying force equilibrium condition of a rigid body. The simulation was modeled according to a real model of Metro Kapsul. The results showed that both values could be categorized as comfortable based on ASCE 21.2-2008. From this study, the safe longitudinal acceleration and deceleration of Metro Kapsul were obtained, i.e. 0.90 m/s2 and 0.97 m/s2, respectively, while the emergency longitudinal deceleration is 1.25 m/s2. When cornering, the maximum velocity is limited by the centrifugal acceleration, which is 0.6 m/s2. To conclude, the current design of Metro Kapsul is already good in steady-state performance. Further research is required for full dynamic and transient conditions with track irregularities.

English

The determination of the cost of agricultural production is an important tool for controlling and managing productive activities and generating information to support decision-making. The objective of this work was to make technical and economic evaluations of three mechanized tomato harvesting systems for industrial processing through the study of times, movements and the determination of operational costs. The research was conducted during the year 2018 in the municipality of Morrinhos-GO. The productive and unproductive times were collected, and subsequently, an economic analysis of each one as well as the calculation of the internal rate of return according to the useful life of each system were performed. After the data collection and analysis, it was concluded that the productive and unproductive times were similar for the evaluated systems. Only the system formed by the harvester, tractor, hauling and bucket was different from the others in relation to the values in US$ h-1 and US$ ha-1. From the fourth year, the internal rate of return was positive for all systems evaluated. Key words: Costs of production, times and motion study, Solanum lycopersicum. &nbsp

Technical and economical evaluation of grid-connected renewable power generation system for a residential urban area

This research investigates the techno-economic assessment of a hybrid grid system of solar and wind power for a residual urban area in Khvaf town located in the eastern part of Iran. The temperature profiles of a 10-year period are gathered based on the existing solar and wind condition data. Simulation, economical and technical evaluations of this hybrid system are studied with the aid of HOMER software. To reach a proper independent structure from the total net present cost and energy cost viewpoints, thousands of cases were studied. Change of the factor investing on PV panels together with the amount of the sun radiance as well as change of the investment factor of wind turbines with the consideration of wind velocity and sun radiance on the system layout are studied and discussed. The initial investment is 440 thousand dollars and the contribution portion of the renewable energies is 84% for the case containing four wind turbines and a power grid system (optimal system). This optimal system returns the investment over a 4-year period which is very economically attractive. The optimal system for the case with a low mean wind speed of 3 m/s is preferred to involve 13-kW photovoltaic (PV) panels, one-wind turbine and a 10-kW converter with a power grid network. Results shown that when the cost of the PV panel is 0.6 times higher than the current cost, a system consisting 4-wind turbines connected to the grid network is still the optimal system. In addition, a sensitivity analysis is made on the load demand of the hybrid system and the renewable energy resource. As a result, the most influential variables on the performance of the system are identified in this research. Based on the economic and technical evaluation, establishing a hybrid grid system for a residential urban area is perfectly reasonable with the investment return during the fourth year of a 25-year project lifetime. Also, among the systems studied, a system with four wind turbines and a power grid system is chosen as an optimal system due to the fact that the region has favorable potential for wind energy.

Feasibility Analysis of Energy Storage Technologies in Power Systems for Arid Region

The benefits of energy storage technologies (ESTs) as a step of managing the future energy demand, by considering the case of electric power systems (EPS) in arid regions, were the focus of this study. The evaluation of different forms of ESTs' integration into the existing EPS, especially those with higher potential for solving issues related to the optimization of the power supply and high demands at peak loads, was carried out. Two interactive programs—ESCT and ES-Select—were utilized in the feasibility study that allowed evaluating various ESTs with regard to their characteristics, costs, benefits, which was carried out for the first time in this region. The study analyzed a variety of power ranges within the power system components including bulk generation, transmission, distribution, commercial and industrial, and residential users. These programs were used to address the price and cost components assuming a normal distribution, as well as the cycle life, size, efficiency, cash flow, payback, benefits range, and market potential of 19 important ESTs about the arid region. The obtained data were all combined to verify the appropriateness of these ESTs, which has been followed by determining the optimal use and best probable physical placement of these ESTs within the EPS, by allowing for the economic, environmental, and technical feasibility. The study showed that the compressed air energy storage (CAES) is the most promising option followed by pumped hydro storage (PHS) and sodium-sulfur battery (NaS), based on the technical and economic evaluations of the different ESTs in arid regions.

Design and Development of a Modular, Multichannel Photoplethysmography System

In this paper, we present the design, development, and validation of a ‘modular photoplethysmography (PPG) system called ZenPPG. This portable, dual-channel system has the capability to produce “raw” PPG signals at two different wavelengths using commercial and/or custom-made PPG sensors. The system consists of five modules, each consisting of circuitry required to perform specific tasks, and are all interconnected by a system bus. The ZenPPG system also facilitates the acquisition of other physiological signals on-demand including electrocardiogram (ECG), respiration, and temperature signals. This report describes the technical details and the evaluation of the ZenPPG along with results from a pilot in vivo study on healthy volunteers. The results from the technical evaluations demonstrate the superiority and flexibility of the system. Also, the systems’ compatibility with commercial pulse oximetry sensors such as the Masimo reusable sensors was demonstrated, where good quality raw PPG signals were recorded with the signal-to-noise ratio (SNR) of 50.65 dB. The estimated arterial oxygen saturation (SpO2) values from the system were also in close agreement with commercial pulse oximeters, although the accuracy of the reported SpO2 value is dependent on the calibration function used. Future work is targeted toward the development of variations of each module, including the laser driver and fiber optic module, onboard data acquisition and signal processing modules. The availability of this system will help researchers from a wide range of disciplines to customize and integrate the ZenPPG system to their research needs and will most definitely enhance research in related fields.

Surgical Simulation: Markers of Proficiency

Surgical simulation has become an integral component of surgical training. Simulation proficiency determination has been traditionally based upon time to completion of various simulated tasks. We aimed to determine objective markers of proficiency in surgical simulation by comparing novel assessments with conventional evaluations of technical skill. Categorical general surgery residents completed 10 laparoscopic cholecystectomy modules using a high-fidelity simulator. We recorded and analyzed simulation task times, as well as number of hand movements, instrument path length, instrument acceleration, and participant affective engagement during each simulation. Comparisons were made to Objective Structured Assessment of Technical Skill (OSATS) and Accreditation Council for Graduate Medical Education Milestones, as well as previous laparoscopic experience, duration of laparoscopic cholecystectomies performed by participants, and postgraduate year. Comparisons were also made to Fundamentals of Laparoscopic Surgery task times. Spearman's rho was utilized for comparisons, significance set at >0.50. University of Missouri, Columbia, Missouri, an academic tertiary care facility. Fourteen categorical general surgery residents (postgraduate year 1-5) were prospectively enrolled. One hundred forty simulations were included. The number of hand movements and instrument path lengths strongly correlated with simulation task times (ρ 0.62-0.87, p < 0.0001), FLS task completion times (ρ 0.50-0.53, p < 0.0001), and prior real-world laparoscopic cholecystectomy experience (ρ -0.51 to -0.53, p < 0.0001). No significant correlations were identified between any of the studied markers with Accreditation Council for Graduate Medical Education Milestones, Objective Structured Assessment of Technical Skill evaluations, total previous laparoscopic experience, or postgraduate year level. Neither instrument acceleration nor participant engagement showed significant correlation with any of the conventional markers of real-world or simulation skill proficiency. Simulation proficiency, measured by instrument and hand motion, is more representative of simulation skill than simulation task time, instrument acceleration, or participant engagement.