1,176,333 research outputs found

    Experimental investigation of a helicopter rotor with Gurney flaps

    Get PDF
    The present work describes an experimental activity carried out to investigate the performance of Gurney flaps on a helicopter rotor model in hovering. The four blades of the articulated rotor model were equipped with Gurney flaps positioned at 95% of the aerofoil chord, spanning 14% of the rotor radius. The global aerodynamic loads and torque were measured for three Gurney flap configurations characterised by different heights. The global measurements showed an apparent benefit produced by Gurney flaps in terms of rotor performance with respect to the clean blade configuration. Particle image velocimetry surveys were also performed on the blade section at 65% of the rotor radius with and without the Gurney flaps. The local velocity data was used to complete the characterisation of the blade aerodynamic performance through the evaluation of the sectional aerodynamic loads using the the control volume approach

    Role Of Embolic Protection In Transcatheter Aortic Valve Replacement: Results From The Deflect I Study

    Get PDF
    Utilization of a cerebral protection device during transcatheter aortic valve replacement (TAVR) will reduce the rate of periprocedural stroke as well as the occurrence and volume of new lesions on diffusion weighted magnetic resonance imaging (DW-MRI), which may serve as a potential surrogate endpoint for clinical studies. The DEFLECT I study is a prospective, multi-center, single arm study that aims to demonstrate the safety and performance of the TriGardTM Embolic Deflection Device (EDD) (Keystone Heart, Caesarea Business Park, Israel), among patients undergoing TAVR. Primary endpoints were device performance and in-hospital device-related safety. A powered secondary endpoint was the number and volume of new DW-MRI brain lesions. Of the 20 consecutive patients enrolled, the device performed as intended with complete vessel coverage until completion of the valve implant in 80% of cases. The hierarchical composite in-hospital procedure-related major adverse cardiac and cerebrovascular (MACCE) event rates was 10% due to 2/20 major disabling strokes, which occurred the day after the procedure following urgent surgery for a failed TAVR implant and a cardiac arrest due to loss of pacer capture. Compared with historical controls, the number of new ischemic brain lesions detected on DW-MRI were similar (70% vs. 76%); however, patients undergoing TAVR with the TriGardTM EDD device demonstrated a 94% reduction in the maximum lesion volume, a 94% reduction in maximum total lesion volume, and a 65% reduction in mean lesion volume compared with historical controls. An angiographic sub-study demonstrated that the only clinical factor associated with the maintenance of device coverage throughout the procedure was anchorage of the upper stabilizer in the innominate artery. The DEFLECT I study established proof of concept of the TriGardTM device and justifies further evaluation in a planned randomized clinical trial

    Evaluation of preformed particle gel as a diverting agent for acidizing

    Get PDF
    Preformed particle gels (PPGs) have been developed and successfully used to improve conformance in heterogeneous reservoirs. However, no research has been reported to show their potential diverting applications in acidizing because of their unknown performance in this process. This work targets on evaluating the potential of PPGs to be used as diverting agents and factors influencing the diverting performance. The swelling properties of three types of PPGs (PPG #1, #2, and #3) were first studied in brine and acid, including the swelling kinetics and equilibrium, PPG strength, and deswelling performance. Effects of different brine concentration, acid concentration, and temperature were also conducted. Then, coreflooding experiments were carried out to investigate their plugging, acid diversion, and permeability recovery performance in carbonate rocks. Effects of PPGs injection volume and particle size were finally investigated. PPG #1 and #2 can swell up to about 10 times and maintain stable in acid for about one day before deswelling. Moreover, PPG #2 even swells a little more in acid at first several hours at 45ā„ƒ. PPG #3\u27s swelling ratio ranges from 20 to 65, which is sensitive to the brine concentration and it reaches deswelling equilibrium after 20 minutes in acid. The gel strength of PPG #2 is the highest and it can be degraded in brine at 80Ā°C in five days. Coreflooding results show that these three PPGs have different diversion ability and can be used as diverting agents to enhance the acid stimulation. Larger injection volume and large particles are favorable by using PPGs as diverting agents in acidizing. The properties evaluation and coreflooding experiments show that PPG #2 can be the best candidate as a diverting agent --Abstract, page iii

    Associations of cognitive reserve and psychological resilience with cognitive functioning in subjects with cerebral white matter hyperintensities

    Get PDF
    Background and purpose Cerebral small vessel disease is characterized by progressive white matter hyperintensities (WMH) and cognitive decline. However, variability exists in how individuals maintain cognitive capabilities despite significant neuropathology. The relationships between individual cognitive reserve, psychological resilience and cognitive functioning were examined in subjects with varying degrees of WMH. Methods In the Helsinki Small Vessel Disease Study, 152 subjects (aged 65-75 years) underwent a comprehensive neuropsychological assessment, evaluation of subjective cognitive complaints and brain magnetic resonance imaging with volumetric WMH evaluation. Cognitive reserve was determined by education (years) and the modified Cognitive Reserve Scale (mCRS). Psychological resilience was evaluated with the Resilience Scale 14. Results The mCRS total score correlated significantly with years of education (r = 0.23, p < 0.01), but it was not related to age, sex or WMH volume. Together, mCRS score and education were associated with performance in a wide range of cognitive domains including processing speed, executive functions, working memory, verbal memory, visuospatial perception and verbal reasoning. Independently of education, the mCRS score had incremental predictive value on delayed verbal recall and subjective cognitive complaints. Psychological resilience was not significantly related to age, education, sex, WMH severity or cognitive test scores, but it was associated with subjective cognitive complaints. Conclusions Cognitive reserve has strong and consistent associations with cognitive functioning in subjects with WMH. Education is widely associated with objective cognitive functioning, whereas lifetime engagement in cognitively stimulating leisure activities (mCRS) has independent predictive value on memory performance and subjective cognitive complaints. Psychological resilience is strongly associated with subjective, but not objective, cognitive functioning.Peer reviewe

    ANALISA KINERJA JALAN LUAR KOTA PADA RUAS JALAN SOEKARNO-HATTA KM. 65+000 - KM. 85+000

    Get PDF
    Andi Rifkie Irawan , NPM : 10.11.1001.7311. 223 , Street Performance Analysis On The Road Soekarno - Hatta Segment KM . 65 + 000 TO KM . 85 + 000 , Supervisor I : Ir. H. Benny Mochtar EA, MT. And Supervisor II : Rossa Agustaniah, ST.,MT.It is the capital city of Samarinda in East Kalimantan has a mining license The Very strategic That connects several districts / cities in the area are the initials , so that the growth of the city of Samarinda High Enough EVERY year. BETWEEN initial situation causes an imbalance in the Period Vehicle WITH capacity Yang Number : Available , so the issue of Traffic and Traffic Accidents And Vehicles queue length. As Happens at Soekarno Hatta Street Segment - KM . 65+ 000 TO KM. 85 + 000 in the area are the initials Many vehicles passing by . FOR THAT THERE Must Re- evaluation of the boarding costs went down the road. Composition Composition Of Husband research is to analyze the boarding costs pada road street sunset Soekarno - Hatta KM 65 + 000 Up to KM 85 + 000 Composition Composition Of Research husband is as follows :Ā 1. Analyze the Initial ConditionsAnalyze the condition changes during peak hours Passes Traffic And the average - average boarding costs went down the road at rush hourFrom the analysis of Jalan Soekarno - Hatta KM 65 + 000 - KM 85 + 000 To conclude ;a. Vehicle flow ( Q )- Segment I: 494 veh / h- Segment II : 507 veh / h b . Capacity ( C )- Segment I: 473 smp / hour- Segment II : 495 smp / hourc . The degree of saturation ( DS )- Segment I: 0.18- Segment II : 0.19 d . barriers side- Segment I: 64 Indicators of Genesis ( L ) Low- Segment II : 49 Indicators of Genesis ( L ) Low e . SPEED And Travel Time- Segment I: 65 km / h and takes 5.5 seconds- Segment II : 64 km / h and takes 5.6 secondsĀ 2. Based Indicators index Service Level ( Level of Service ) / LOS Roads Soekarno Hatta( Samarinda - Balikpapan ) Kilometer 65 s/d 85 Kilometers is :The ratio obtained L.o.S = V / C- Segment I: 473 / 2648.1 = 0.18 < 0.85 = B- Segment II : 495 / 2648.1 = 0.19 < 0.85 = BĀ Indicators derived from the index calculation Service Level B OR < 0.85 it can be concluded that free prepaid Flow , Low Volume , High SPEED , and Drivers MAY require speed , expandabilas SPEED What is desired

    A compact photoreactor for automated H2 photoproduction: Revisiting the (Pd, Pt, Au)/TiO2 (P25) Schottky junctions

    Get PDF
    The configuration and geometry of chemical reactors underpins the accuracy of performance evaluation for photocatalytic materials and, accordingly, the development and validation of thermodynamic and kinetic model reactions. The lack of accurate photonic, mass, and heat transport profiles for photochemical reactors hinder standardization, scale-up, and ultimately comparison between different experiments. This work proposes two contributions at the interface between engineering of chemical process and materials science: (A) an automated compact stainless-steel photoreactor with 40 cm3 and 65 cm2 of volume and area, respectively, for hydrogen photoproduction as a model reaction and (B) the synthesis, characterization, and performance of TiO2 Schottky junctions, using Pd, Pt, or Au nanoparticles (ca. 0.5, 1, 2 wt% loadings each) to validate the operation of the reactor. A photonic profile methodology is implemented to the studied reactor to obtain the local light absorption profile, opening up for evaluation of the local quantum yield calculation for the selected materials. A combination of transmission electron microscopy, (X-ray/ultraviolet) photoelectron/electron, energy loss/infrared spectroscopies, X-ray scattering, inductively coupled plasma atomic emission spectroscopy, and ultravioletā€“visible spectrophotometry is employed to determine the distinctive surface and bulk properties to build structureā€“function correlations. The (Pd, Pt, Au)/TiO2 Schottky junction exhibits H2 production rates slightly higher than previous studies, with quantum yields almost 2-fold higher than reported values. These results, demonstrate that the proposed novel geometry of the photoreactor improves the photonic, heat, and mass profiles. An in-depth analysis of the Au plasmon was investigated coupling electron energy loss spectroscopy, UVā€“vis, and transmission electron microscope, resulting in insightful information about the Au NP mode at the TiO2 interface

    Facile Synthesis of Ordered Mesoporous Orthorhombic Niobium Oxide (T-Nb2_2O5_5) for High-Rate Li-Ion Storage with Long Cycling Stability

    Get PDF
    Herein, we describe the synthesis and evaluation of hierarchical mesoporous orthorhombic niobium oxide (T-Nb2_2O5_5) as an anode material for rechargeable lithium-ion batteries (LIB). The as-synthesized material addresses key challenges such as beneficial porous structure, poor rate capability, and cycling performance of the anode for Li-ion devices. The physicochemical characterization results reveal hierarchical porous nanostructure morphology with agglomerated particles and a 20 to 25 nm dimension range. Moreover, the sample has a high specific surface area (~65 m2^2 gāˆ’1^{āˆ’1}) and pore volume (0.135 cm3 gāˆ’1^{āˆ’1}). As for the application in Li-ion devices, the T-Nb2_2O5_5 delivered an initial discharging capacity as high as 225 mAh gāˆ’1^{āˆ’1} at 0.1 A gāˆ’1^{āˆ’1} and higher rate capability as well as remarkable cycling features (~70% capacity retention after 300 cycles at 250 mA gāˆ’1^{āˆ’1}) with 98% average Coulombic efficiency (CE). Furthermore, the scan rate-dependent charge storage mechanism of the T-Nb2_2O5_5 electrode material was described, and the findings demonstrate that the electrode shows an evident and highly effective pseudocapacitive Li intercalation behaviour, which is crucial for understanding the electrode process kinetics. The origin of the improved performance of T-Nb2_2O5_5 results from the high surface area and mesoporous structure of the nanoparticles

    Large-scale Hierarchical Alignment for Data-driven Text Rewriting

    Full text link
    We propose a simple unsupervised method for extracting pseudo-parallel monolingual sentence pairs from comparable corpora representative of two different text styles, such as news articles and scientific papers. Our approach does not require a seed parallel corpus, but instead relies solely on hierarchical search over pre-trained embeddings of documents and sentences. We demonstrate the effectiveness of our method through automatic and extrinsic evaluation on text simplification from the normal to the Simple Wikipedia. We show that pseudo-parallel sentences extracted with our method not only supplement existing parallel data, but can even lead to competitive performance on their own.Comment: RANLP 201

    Design and performance evaluation of the secure tranmission module for three-dimensional medical image system based on Web PACS

    Get PDF
    PACS is a medical system for digital medical images, and PACS expand to web-based service using public network, DICOM files should be protected from the man-in-the-middle attack because they have personal medical record. To solve the problem, we designed flexible secure transmission system using IPSec and adopted to a web-based three-dimensional medical image system. And next, we performed the performance evaluation changing integrity and encryption algorithm using DICOM volume dataset. At that time, combinations of the algorithm was ā€˜DES-MD5ā€™, ā€˜DES-SHA1ā€™, ā€˜3DES-MD5ā€™, and ā€˜3DES-SHA1, and the experiment was performed on our test-bed. In experimental result, the overall performance was affected by encryption algorithms than integrity algorithms, DES was approximately 50% of throughput degradation and 3DES was about to 65% of throughput degradation. Also when DICOM volume dataset was transmitted using secure transmission system, the network performance degradation had shown because of increased packet overhead. As a result, server and network performance degradation occurs for secure transmission system by ensuring the secure exchange of messages. Thus, if the secure transmission system adopted to the medical images that should be protected, it could solve server performance gradation and compose secure web PACS.ope

    Multicenter clinical evaluation of the Luminex Aries Flu A/B & RSV assay for pediatric and adult respiratory tract specimens

    Get PDF
    ABSTRACT Influenza A and B viruses and respiratory syncytial virus (RSV) are three common viruses implicated in seasonal respiratory tract infections and are a major cause of morbidity and mortality in adults and children worldwide. In recent years, an increasing number of commercial molecular tests have become available to diagnose respiratory viral infections. The Luminex Aries Flu A/B &amp; RSV assay is a fully automated sample-to-answer molecular diagnostic assay for the detection of influenza A, influenza B, and RSV. The clinical performance of the Aries Flu A/B &amp; RSV assay was prospectively evaluated in comparison to that of the Luminex xTAG respiratory viral panel (RVP) at four North American clinical institutions over a 2-year period. Of the 2,479 eligible nasopharyngeal swab specimens included in the prospective study, 2,371 gave concordant results between the assays. One hundred eight specimens generated results that were discordant with those from the xTAG RVP and were further analyzed by bidirectional sequencing. Final clinical sensitivity values of the Aries Flu A/B &amp; RSV assay were 98.1% for influenza A virus, 98.0% for influenza B virus, and 97.7% for RSV. Final clinical specificities for all three pathogens ranged from 98.6% to 99.8%. Due to the low prevalence of influenza B, an additional 40 banked influenza B-positive specimens were tested at the participating clinical laboratories and were all accurately detected by the Aries Flu A/B &amp; RSV assay. This study demonstrates that the Aries Flu A/B &amp; RSV assay is a suitable method for rapid and accurate identification of these causative pathogens in respiratory infections.</jats:p
    • ā€¦
    corecore