Similar Output Research Articles

Implementation of Dryden Continuous Turbulence Model into Simulink for LSA-02 Flight Test Simulation

Turbulence is a movement of air on small scale in the atmosphere that caused by instabilities of pressure and temperature distribution. Turbulence model is integrated into flight mechanical model as an atmospheric disturbance. Common turbulence model used in flight mechanical model are Dryden and Von Karman model. In this minor research, only Dryden continuous turbulence model were made.Dryden continuous turbulence model has been implemented, it refers to the military specification MIL-HDBK-1797. The model was implemented into Matlab Simulink. The model will be integrated with flight mechanical model to observe response of the aircraft when it is flight through turbulence field. The turbulence model is characterized by multiplying the filter which are generated from power spectral density with band-limited Gaussian white noise input.In order to ensure that the model provide a good result, model verification has been done by comparing the implemented model with the similar model that is provided in aerospace blockset. The result shows that there are some difference for 2 linear velocities (vg and wg), and 3 angular rate (pg, qg and rg). The difference is instantly caused by different determination of turbulence scale length which is used in aerospace blockset. With the adjustment of turbulence length in the implemented model, both model result the similar output.

On the value of foreign PhDs in the developing world: Training versus selection effects in the case of South Africa

When seeking to improve science in emerging economies, uncertainty exists whether PhD training in an emerging economy can yield comparable results to PhD training in the developed world. Scientific achievements may vary because of excellent training at good universities, but also because excellent students select (and are selected by) good universities. This paper compares the career effects of overseas and domestic PhD training for scholars working in an emerging economy, South Africa. We differentiate between and examine both selection and training effects for PhDs from three tiers of South African and two tiers of foreign universities. South African academics with PhDs from universities in industrialised countries generally achieve greater career success than those with local PhDs, but training by universities in industrialised countries is not necessarily better than local training. Our results suggest that the perceived superiority of foreign PhD training stems from selection rather than do training effects, and pure selection effects in fact explain career outcomes better than training effects. Focusing on training rather than selection, PhDs from top South African universities produce a similar quantity and quality research output to those trained by the leading universities in the developed world. From the perspective of an emerging economy with limited resources wishing to advance science, the development of local universities should thus be stressed, although it is clear that individuals who are able to study for a PhD abroad gain personally when they return.

Performance analysis of partially recuperative gas turbine combined cycle under off-design conditions

A partially recuperative gas turbine combined cycle (GTCCpr) is proposed in this paper to improve the off-design performance of power plants. The performance coupling with a new operation strategy is also analyzed. In the proposed GTCCpr, the gas flow at the outlet of the turbine is divided into two streams, and only a part of exhaust gas from the turbine is used to preheat the outlet air of the compressor. Exhaust gas streams from the recuperator are mixed with flue from the second reheater at the inlet of the first reheater to achieve similar temperature level. Specifically, the fraction of exhaust gas that preheats air can be changed to adjust the load of the combined cycle. The PG9351FA gas turbine unit is selected as the reference unit for comparison. Then, the design/off-design characteristics of the two cycles are compared and analyzed with the same turbine initial temperature. Results indicate that the partially recuperative GTCCpr running with the new operation has better off-design performances than the reference unit with approximately 1.7% maximum difference of efficiency. At the design point, the exhaust gas used for partial recuperation only accounts for 10% of the total mass, and the effect of recuperation is not evident. Therefore, the two cycles possess nearly similar output and efficiency. The efficiency of partially recuperative GTCCpr is nearly unchanged with the increasing recuperative mass fraction, which changes its specific power to adjust the load. At low loads, with decreasing turbine exhaust gas temperature, the efficiency improvement also decreases due to the partial recuperation. A comprehensive comparison with the reference unit revealed that GTCCpr with the proposed “recuperation adjustment” method can maintain a higher off-design efficiency and slightly lower design power output compared with the conventional cycle. Specific power adjustment of recuperation is one of the efficient methods for load adjustment, and GTCCpr is one of the best options.

Towards Generation of Effective 3D Surface Models from UAV Imagery Using Open Source Tools

There has been increasing popularity in large scale mapping for deriving 3D surface and elevation models of earth and building structures. The techniques of computer vision comprising feature detections and matching and photogrammetry play an important role in deriving near accurate 3D reconstruction of scenes from 2D images. Since the images captured by the unmanned aerial vehicle (UAVs) are of high resolution, there is need for more sophisticated processing and analysis of the imagery to generate 3D models and other useful imagery products. The open source softwares are excellent tools for research and can be modified or changed to suit our model, as specific or combinations of algorithms behave differently based on the nature of UAV image scene to be processed. Though many algorithms are available for performing feature extractions from images, few studies have been carried out to identify suitable detector algorithms to be used based on the nature of image or scene that the UAV captures. An attempt has been made to understand and analyse the suitability of feature detection and descriptor algorithms for different scene types. This article also describes the popular technique called structure from motion process pipeline for sequential processing of UAV images with high overlapping, which involves the estimation of 3D point clouds from the keypoint correspondences. The relative accuracy of the 3D point cloud derived from our approach is comparable with similar output from other state-of-the-art UAV processing systems and is found to match with high precision.

AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire

The performance characteristics of AlGaN-based deep ultraviolet light emitting diodes (UV-LEDs) grown by metalorganic vapor phase epitaxy on sputtered and high temperature annealed AlN/sapphire templates are investigated and compared with LEDs grown on epitaxially laterally overgrown (ELO) AlN/sapphire. The structural and electro-optical properties of the devices on 350 nm sputtered and high temperature annealed AlN/sapphire show similar defect densities and output power levels as LEDs grown on low defect density ELO AlN/sapphire templates. After high temperature annealing of the 350 nm sputtered AlN, the full widths at half maximum of the (0002) and (101¯2) reflections of the high resolution x-ray diffraction rocking curves decrease by one order of magnitude to 65 arc sec and 240 arc sec, respectively. The curvature of the sputtered and HTA AlN/sapphire templates after regrowth with 400 nm MOVPE AlN is with −80 km−1 much lower than the curvature of the ELO AlN/sapphire template of −160 km−1. The on-wafer measured output powers of 268 nm LEDs grown on 350 nm sputtered and high temperature annealed AlN/sapphire templates and ELO AlN/sapphire templates were 0.70 mW and 0.72 mW at 20 mA, respectively (corresponding to an external quantum efficiency of 0.75% and 0.78%). These results show that sputtered and high temperature annealed AlN/sapphire provide a viable approach for the fabrication of efficient UVC-LEDs with reduced complexity and thus reduced costs.

Optical frequency combs based on a period-doubling mode-locked Er-doped fiber laser.

The phase-locking mechanism and results of a frequency comb based on a period-doubling mode-locked (PD-ML) fiber laser were investigated. A mode-locked fiber laser was designed to switch from fundamental mode locking (FML) to PD-ML with similar output pulses by simply changing the pump. Experimental results show that the new comb teeth generated in the PD-ML are strongly correlated with the original teeth and have a consistent carrier-envelope offset (CEO) frequency. Controlling the pump and cavity length is also suited for phase-locking the PD-ML laser. With the same f-to-2f heterodyne beat system and locking circuit, phase locking of both PD-ML and FML-based optical combs with two repetition rates, and switching between them, were obtained by changing the pump only.

Classification and Prediction on Rural Property Mortgage Data with Three Data Mining Methods

The Farmers Property Mortgage Policy is a strategic financial policy in western China, a relatively underdeveloped region. Many contradictions and conflicts exist in the process between the strong demand for the loans by farmers and the strict risk control by the financial institutions. The rural finance corporations should use scientific analysis and investigation of the potential households for overall evaluation of the customers. These include historical credit rating, present family situation, and other related information. Three different data mining methods were applied in this paper to the specifically-collected household data. The objective was to study which factor could be the most important in determining loan demand for households, and in the meanwhile, to classify and predict the possibility of loan demand for the potential customers. The results obtained from the three methods indicated the similar outputs, income level, land area, the way of loan, and the understanding of policy were four main factors which decided the probability of one specific farmer applying for a credit loan. The results also embodied the difference within the three methods for classifying and predicting the loan anticipation for the testing households. The artificial neural network model had the highest accuracy of 91.4 which is better than the other two methods.

The rise of Portuguese Antarctic research: implications for Portugal's status under the Antarctic Treaty

ABSTRACTPortugal has developed an active Antarctic programme over the past decade. Here, we examine Portuguese Antarctic activity using a variety of bibliometric measures, showing that Portuguese scientific output has grown substantially faster than the field as a whole, with quality remaining broadly constant. Antarctic science made up a growing percentage of overall Portuguese research, up to 0.14% of all papers in 2016—a level comparable to many other nations with well-established research programmes. Alongside this, Portugal has increasingly engaged in policy discussions and produced policy papers for Antarctic Treaty Consultative Meetings, some of which were based on Portuguese environmental science. The Antarctic Treaty reserves decision-making powers to ‘Consultative Parties’—those who have been recognised as demonstrating substantial research activity in the continent. Our data indicates that Portugal is currently the fourth most productive non-Consultative Party, and has similar or greater output than several Parties who have already attained consultative status—its publication record is similar to that of the Czech Republic, which became a Consultative Party in 2014. The rapid growth of Portugal's Antarctic research may make it well placed to consider attaining consultative status to the Antarctic Treaty in the near future.

Environmental impact of emissions from incineration plants in comparison to typical heating systems

In recent years, five modern municipal waste incineration plants have been built in Poland. Next ones are being constructed and at the same time building of several others is being considered. Despite positive experience with the operation of the existing installations, each project of building a new incinerator raises a lot of emotions and social protests. The main argument against construction of an incineration plant is the emission of pollutants. The work compares emissions from municipal waste incineration plants with those from typical heating plants: in the first part, for comparison large heating plants equipped with pulverized coal-fired boilers (OP-140), stoker-fired boilers (three OR-32 boilers) or gas blocks with heat output of about 100 MW have been selected, while the second part compares WR-10 and WR-25 stoker-fired boilers most popular in our heating industry with thermal treatment systems for municipal waste or refuse-derived-fuel (RDF) with similar heat output. Both absolute emission and impact - immission of pollutants in vicinity of the plant were analyzed.

A Novel Method of Evaluating Key Factors for Success in a Multifaceted Critical Care Fellowship Using Data Envelopment Analysis.

The current system of summative multi-rater evaluations and standardized tests to determine readiness to graduate from critical care fellowships has limitations. We sought to pilot the use of data envelopment analysis (DEA) to assess what aspects of the fellowship program contribute the most to an individual fellow's success. DEA is a nonparametric, operations research technique that uses linear programming to determine the technical efficiency of an entity based on its relative usage of resources in producing the outcome. Retrospective cohort study. Critical care fellows (n = 15) in an Accreditation Council for Graduate Medical Education (ACGME) accredited fellowship at a major academic medical center in the United States. After obtaining institutional review board approval for this retrospective study, we analyzed the data of 15 anesthesiology critical care fellows from academic years 2013-2015. The input-oriented DEA model develops a composite score for each fellow based on multiple inputs and outputs. The inputs included the didactic sessions attended, the ratio of clinical duty works hours to the procedures performed (work intensity index), and the outputs were the Multidisciplinary Critical Care Knowledge Assessment Program (MCCKAP) score and summative evaluations of fellows. A DEA efficiency score that ranged from 0 to 1 was generated for each of the fellows. Five fellows were rated as DEA efficient, and 10 fellows were characterized in the DEA inefficient group. The model was able to forecast the level of effort needed for each inefficient fellow, to achieve similar outputs as their best performing peers. The model also identified the work intensity index as the key element that characterized the best performers in our fellowship. DEA is a feasible method of objectively evaluating peer performance in a critical care fellowship beyond summative evaluations alone and can potentially be a powerful tool to guide individual performance during the fellowship.

Dimensional assessment of a low power combined cycle system for hybrid propulsion

The paper presents the results of the study referring to both size and mass of the Low Power Combined Cycle system. A previous study referring to the performance indicates that a natural gas fueled Low Power Combined Cycle system – based on a gas turbine engine with heat exchanger and a steam turbine engine with two pressure levels – should be significantly more efficient than current diesel engines with similar output powers. Due to this fact, hybrid propulsion based on the mentioned system stands out as an advantageous solution for the terrestrial transport field. Beside the requirement related to performance, compliance with the assigned space and mass limitation are another compulsory requirements of any propulsion system. This subject is analyzed inside the paper.

Integrated Model of Image Protection Techniques

We propose an integrated model of Block-Permutation-Based Encryption (BPBE) and Reversible Data Hiding (RDH). The BPBE scheme involves four processes for encryption, namely block scrambling, block-rotation/inversion, negative-positive transformation and the color component shuffling. A Histogram Shifting (HS) method is adopted for RDH in our model. The proposed scheme can be well suitable for the hierarchical access control system, where the data can be accessed with the different access rights. This scheme encrypts R, G and B components independently. Therefore, we can generate similar output images from different input images. Additionally, the key derivation scheme also provides the security according to the different access rights. Our scheme is also resilient against brute-force attacks and Jigsaw Puzzle Solvers (JPSs). Furthermore, the compression performance is also not severely degraded using a standard lossless compression method.

Multiresponse algorithms for community‐level modelling: Review of theory, applications, and comparison to species distribution models

Abstract Community‐level models (CLMs) consider multiple, co‐occurring species in model fitting and are lesser known alternatives to species distribution models (SDMs) for analysing and predicting biodiversity patterns. Community‐level models simultaneously model multiple species, including rare species, while reducing overfitting and implicitly considering drivers of co‐occurrence. Many CLMs are direct extensions of well‐known SDMs and therefore should be familiar to ecologists. However, CLMs remain underutilized, and there have been few tests of their potential benefits and no systematic reviews of their assumptions and implementations. Here, we review this emerging field and provide examples in r to fit common CLMs. Our goal is to introduce CLMs to a broader audience, and discuss their attributes, benefits and limitations relative to SDMs. We review (1) statistical implementations and applications of CLMs, (2) their advantages and limitations, and (3) comparative analyses of CLMs and SDMs. We also suggest directions for future research. We identify seven CLM algorithms with similar data structures and predictive outputs as SDMs that should be most accessible to ecologists familiar with species‐level modelling, including five methods that predict assemblage composition and individual species distributions and two methods that model compositional turnover along environmental gradients. Community‐level models have been applied to numerous taxa, regions, and spatial scales, and a variety of topics (e.g. studying drivers of community structure or assessing relationships between community composition and functional traits). Studies suggest that the relative benefits of CLMs and SDMs may be case specific, especially in terms of predicting species distributions and community composition. However, CLMs may offer advantages in terms of computational efficiency, modelling rare species, and projecting to no‐analog climates. A major shortcoming of CLMs is their reliance on presence–absence community composition data. Studies are needed to assess the relative merits of SDMs and CLMs, and different CLM algorithms, with a focus on three key areas: (1) under which circumstances CLMs improve predictions for rare species, (2) how CLMs perform under different community compositions (e.g. relative abundance of rare vs. common species), including the extent to which co‐occurrence patterns are structured by biotic interactions, and (3) ability to project across time/space.

Performance of the Commercial PP/ZnS:Cu and PP/ZnS:Ag Scintillation Screens for Fast Neutron Imaging

Fast neutron imaging has a great potential as a nondestructive technique for testing large objects. The main factor limiting applications of this technique is detection technology, offering relatively poor spatial resolution of images and low detection efficiency, which results in very long exposure times. Therefore, research on development of scintillators for fast neutron imaging is of high importance. A comparison of the light output, gamma radiation sensitivity and spatial resolution of commercially available scintillator screens composed of PP/ZnS:Cu and PP/ZnS:Ag of different thicknesses are presented. The scintillators were provided by RC Tritec AG company and the test performed at the NECTAR facility located at the FRM II nuclear research reactor. It was shown that light output increases and the spatial resolution decreases with the scintillator thickness. Both compositions of the scintillating material provide similar light output, while the gamma sensitivity of PP/ZnS:Cu is significantly higher as compared to PP/ZnS:Ag-based scintillators. Moreover, we report which factors should be considered when choosing a scintillator and what are the limitations of the investigated types of scintillators.

Efficiency Measurement of Regional Development Agencies in Turkey by Using Data Envelopment Analysis (DEA)

In this study, relative efficiencies of Regional Development Agencies (RDA) work in Turkey were determined using Data Envelopment Analysis (DEA). The goal of DEA is to measure relative efficiencies of comparable Decision Making Units which produce similar input and output. At the end of the analysis, reference decision making units will be determined for inefficient decision making units. To do this data are gathered from efficiency reports of Regional Development Agencies and based on these data, efficiency scores are calculated. At the end of the study, recommendations are given with the help of findings to improve RDAs performances.

Does Corporate Diversification Induce Financing Choice?

This paper sets out to examine the effect of business diversification strategy on capital structure in Malaysia. The study segregates the firms into related and unrelated firms based on segmentation of Standard Industry Classification Code. It involes 76 public listed firms in Bursa Malaysia from 1994 to 2012. This research uses static panel data to determine the credible association between diversification strategy and choice of financing. The authors find that period fixed effect with seemingly unrelated regression produce better results to explain the relationship between independent and dependent variables. The results demonstrate that there is insignificant relationship between diversification strategy and capital structure. Robustness check on pre and post crisis data generate similar output. The potential contribution of this work lies in offering empirical evidence to test the previous held assumption that there is a significant relationship between corporate expansion and financing decision done by firms. Future research should explore the possibility by using international firms to investigate the association between those variables.

RETRACTED ARTICLE: Test data compression for digital circuits using tetrad state skip scheme

The objective of this research is the assessment of circuit design compression strategy carrying a greater number of similar output chains. The proposed method decreases the testing time while keeping lesser area overhead. The decompression technique depends upon constant LFSR diffusion which is utilized as a part of such a route, to the point that it empowers LFSR lockout getting away inside the least amount of clock series. It involves a different scheming of the LFSR de-compressor and the output set timer inputs. The proposed work presents the tetrad state skip decompression adequacy for various LFSR dimensions, examine chain measurements and quantities of similar LFSR data. Our observations depict that it is equipment sparing to utilize an LFSR by skipping individual states as opposed to employing an LFSR deceased along with a stage shifter. In other words, it uses a lesser amount of interior XOR doors, ensures most last partition between sweep chains without presenting any additional postponement on the LFSR outcomes. Exploratory outcomes have demonstrated that the displayed test design decompression on conventional circuits gives an unlimited blame scope and lesser test duration besides the minor equipment overhead is contrasting the forms composed and the assistance of the recent days’ mechanical instruments.

Comparison of conventional and regenerative electrostatic energy harvesters

This study presents a performance comparison of two green electrostatic energy harvesters based on force‐sensitive mechanically variable capacitors. A startup battery is required in the conventional electrostatic energy harvester to precharge the mechanically variable capacitor. This adds an extra element to the device and increases the harvester's size and weight. The proposed harvester does not need a startup battery, operates in a regenerative mode, and provides a similar output power. It has a compact size and can start from low voltages. The conventional and regenerative harvesters were developed using mechanically variable capacitors fabricated with renewable materials (i.e. nanocellulose and carbon‐coated nanocellulose). The flexible nanocellulose films and the cost‐effective fabrication process make the energy harvesters suitable for powering low‐power and wearable devices. The bio‐based materials further reduce the environmental impact of the devices. Prototypes of the two energy harvesters were built, and their performances were compared on the basis of simulation and measurement results. Both simulation and experimental results are shown to demonstrate the startup and scalable energy availability of the proposed regenerative electrostatic energy harvester for driving low‐power devices, such as wireless sensor networks.

Daily performance of parabolic trough solar collectors

Parabolic trough collector (PTC) is the most mature concentrating technology which is used in a great variety of thermal applications. In this study, the daily performance of a PTC is investigated for all the year period. The module of Eurotrough parabolic trough collector is examined with various storage tanks from 3 m3 to 15 m3 and the collector performance is investigated in energetic and exergetic terms. An Input/Output method is applied for the daily evaluation of the solar thermal system, something innovative for concentrating solar collectors. According to the final results, different storage tank volumes lead to similar thermal outputs but to extremely different exergetic outputs because of the high dependence of the mean storage tank temperature with the storage tank volume. For the storage tank of 9 m3, the mean thermal efficiencies in December and in June are found to be 37.1% and 68.7% respectively, while the mean exergetic efficiencies 2.0% and 8.5% respectively. Moreover, it is proved that the Input/Output performance method in concentrating collectors has to take into consideration the solar incident angle at solar noon in order high accuracy to be achieved.

Acute effects of repeated cycling sprints in hypoxia induced by voluntary hypoventilation.

This study aimed to investigate the acute responses to repeated-sprint exercise (RSE) in hypoxia induced by voluntary hypoventilation at low lung volume (VHL). Nine well-trained subjects performed two sets of eight 6-s sprints on a cycle ergometer followed by 24s of inactive recovery. RSE was randomly carried out either with normal breathing (RSN) or with VHL (RSH-VHL). Peak (PPO) and mean power output (MPO) of each sprint were measured. Arterial oxygen saturation, heart rate (HR), gas exchange and muscle concentrations of oxy-([O2Hb]) and deoxyhaemoglobin/myoglobin ([HHb]) were continuously recorded throughout exercise. Blood lactate concentration ([La]) was measured at the end of the first (S1) and second set (S2). There was no difference in PPO and MPO between conditions in all sprints. Arterial oxygen saturation (87.7 ± 3.6 vs 96.9 ± 1.8% at the last sprint) and HR were lower in RSH-VHL than in RSN during most part of exercise. The changes in [O2Hb] and [HHb] were greater in RSH-VHL at S2. Oxygen uptake was significantly higher in RSH-VHL than in RSN during the recovery periods following sprints at S2 (3.02 ± 0.4 vs 2.67 ± 0.5L min-1 on average) whereas [La] was lower in RSH-VHL at the end of exercise (10.3 ± 2.9 vs 13.8 ± 3.5mmol.L-1; p < 0.01). This study shows that performing RSE with VHL led to larger arterial and muscle deoxygenation than with normal breathing while maintaining similar power output. This kind of exercise may be worth using for performing repeated sprint training in hypoxia.