bluuebunny/crossref_metadata_2025_split huggingface dataset:
Criteria for the Choice of Fans for use in Thermal Power Plant Applications
Authors: Godichon A 
Published: February 2007

Large fans for the thermal power industry operate more and more on part load. This paper discusses how the total cost of an investment is increasingly based on the inclusion of the operating costs. Today there is still a high demand for conventional thermal power stations. New ones are under construction and existing ones are in the process of conversion with new desulfurization units; more and more emphasis is being concentrated on: Operating efficiency Technical reliability The environment and noise and, of course, Return on investment Because these priorities are contradictory, the objective of this paper is to guide the reader to the best choice of fan technology given differing circumstances. The correct choice is important concerning primary air, forced draft, induced draft and booster fans which can represent a total power consumption of 2–4 per cent in a 350–600 MW power plant depending on the quality of coal used and the boiler type. These fans are generally characterized by a large volume flow and a relatively large pressure and can be of the centrifugal or axial type. Many solutions are possible for controlling the air flow of these fans. The main ones will be examined by looking at their general principles, their performance and characteristics, and then comparing them from an energy consumption point of view.
Tolerance Stack Analysis for Assembly
Authors: Ngoi B K A , Tan K C K 
Published: February 2007

Studies have indicated that design for manufacture and design for assembly have a significant impact on the success of a product. One of the key issues is tolerance specification and thus it is important for the designer to consider tolerance analysis thoroughly in the early stages of product development. With minor modifications and if used properly, tolerance charting can be a valuable tool to the product designer. This paper illustrates two methods used to tackle tolerance balancing for assembly and provides an insight into the considerations to be taken into account. A manual method first demonstrates the fundamental concepts while a computer aided version further enhances the charting process. The latter is easy to apply and renders greater flexibility during problem formulation. Consequently, what–if analysis is possible and thus better results can be achieved. However, it should be cautioned that tolerance charts are merely tools; the results they produce can only be as good as the inputs they receive and thus a ‘perfect’ solution cannot be guaranteed. Nonetheless, tolerance charting is an effective diagnostic tool as it provides tolerance analysis in the early stage of products development.
Flow Properties and Passive Scalar Transport in a Model Room With Relevance to Ventilation Efficiency
Authors: Özdemir İ B , Whitelaw J H , Biçen A F 
Published: February 2007

This paper describes an experimental investigation of air flow patterns and related passive scalar transport inside a model room with emphasis on the statistical time-scales of the dispersion process and the local ventilation effectiveness. Time-averaged and instantaneous structures of the turbulent flow were examined by local measurements inside a negatively pressurized cubic enclosure of 2 m side dimension and ventilated through single-supply and exhaust registers at an extract flowrate of 1.81 m3/min with a corresponding air change of 13.6 per hour. Sulphur hexafluoride was introduced at the centre of the enclosure and used to mark the flow. The distributions of its time-averaged concentration inside the room were used to deduce the degree of mixing and passive scalar transport. The measurements of the time-averaged flow field showed that the arrangement with no sources of forced internal mixing resulted in the ventilating flow occurring in a channel connecting the supply and exhaust. Outside this jet-like main stream and particularly in corners, the flow stagnated with high concentrations of the tracer gas in these regions. Time variations of the instantaneous local concentration values at different locations inside the room for a process of purging following steady injection were used to estimate the probability density function of the local residence age whose shape provided further experimental evidence of the prolonged dilution due to pollutant fluid which entered stagnation zones. The results also showed that the statistical time-scales of the dispersion and the mixing efficiency are independent of the level of the steady pollutant generation. The ratio of the mean age to its standard deviation is recommended as a local mixedness factor and comparison with the mixing efficiency defined on the basis of integral time-scales and the exponential decay model revealed that it represents better the local variations, which is essential to assessing local indoor air quality. The extent of validity of the exponential decay model was also evaluated by comparing the time constant of this model with model-independent integral time-scales and it is shown that the underlying assumptions of the exponential decay model precludes the representation of spatial gradients.
A Novel Worm Gear of High Efficiency
Authors: French M J 
Published: February 2007

This note describes a novel form of worm gear, in which the worm pinion has teeth that run straight round it and join up with themselves, so that they form rings (‘ring teeth’). These rings are free to turn on bearings whose axes are parallel to the axis of rotation of the whole pinion, but eccentric to it by a small amount r, such that the centres of the rings lie on a helix, radius r. The teeth of the worm wheel are formed in the inside of a torus, so that they embrace the pinion somewhat. They have a small helical angle so that as a ring tooth rolls round the space between two worm teeth it forces them forward. Before that ring tooth disengages at one side of that worm wheel tooth space, the next ring tooth has engaged with the next wheel tooth space, and so on. Because the ring teeth roll on the wheel teeth, with only a little spin and transverse sliding, the efficiency is very high. However, the construction of the pinion is elaborate and the load capacity of the drive is limited by that of the bearings on which the ring teeth rotate, which in turn is small because of the limits on space.
The Torque–Tension Behaviour of 22 × 1.5 mm Bolts for Fixing Spigot-Located Wheels on Heavy Commercial Vehicles
Authors: Morgan R C , Henshall J L 
Published: February 2007

Threaded fasteners are generally used to secure wheels on to vehicles. However, in the case of heavy commercial vehicles, in recent years there has been a problem of ensuring the integrity of wheel fixings (1, 2). Notwithstanding a change of wheel centring from conically ended nuts to a central hub spigot, essentially the same wheel fixing system is used nowadays as was developed when the operational duty cycles were much lower, for example 80 kN versus 130 kN maximum regular axle loads, increased mileages, markedly improved braking performance, higher speeds, better tyre/road coefficients and greater cornering forces. Consequently a new British Standard concerned with quality control of the components used for commercial vehicle wheel fixings has been published (3). The purpose of the present work is to report the results of an investigation into some of the factors which can affect the performance of the main type of commercial vehicle wheel fastener, in particular the effects of fastener friction on the pre-load. Experiments have been performed on 22 × 1.5 mm wheel bolts and nuts under four different conditions, namely ‘as received’, degreased, heat-cycled and re-lubricated, at torques up to 800 N m. The results showed a substantial decrease, of up to 60–70 per cent, in axial tension for both degreased and heat-cycled conditions, when compared with the ‘as received’ performance. Full recovery was found to be achievable simply by re-lubricating with engine oil. The theoretical torque-tension model (4) was modified to account for the nut–washer geometry and used to determine effective friction coefficients. These, and the other limited published data (5–7) were used to define performance boundaries. A comparison is made between the data presented herein and the quality determining performance as specified in the new British Standard (3).
Measurement of Positive Displacement Pump Flow Ripple and Impedance
Authors: Johnston D N , Drew J E 
Published: February 2007

The secondary source method forms the British Standard for pump fluid-borne noise testing. This is a powerful technique but requires care in order to produce accurate results. This paper describes practical aspects for implementing the method. The requirements for the test rig, data acquisition system and analysis are detailed. The British Standard specifies that either mathematical modelling or linear interpolation is used on the source impedance measurements. A method for smoothing the impedance results is described in this paper, which is shown to give more repeatable results than linear interpolation. Some physically realistic mathematical models of pump impedance are described, and their use in determining the internal flow ripple discussed.
Grassed buffer strips as nitrate diffuse pollution remediation tools: management impact on the denitrification enzyme activity
Authors: Cors M. , Tychon B. 
Published: February 2007

The management of grassed buffer strips proved to be an efficient remediation technique in controlling nitrogen losses to surface water. In south Belgium, agri-environmental policies have encouraged farmers to seed buffer strips along rivers, in zones where the soil was previously devoted to agricultural production.
We wanted to assess how important denitrification is in a buffer strip in comparison with a cropped field. The study investigated the denitrifiying enzyme activity (DEA) of two contiguous buffer strips with different management stories. The eastern part of the buffer strip was seeded in 1999. The western part of the buffer strip is a piece of crop field abandoned by the farmer 20 years ago and not managed for the last 10 years.
This experimental study demonstrates that the denitrification enzyme activity in a riparian buffer strip is significantly higher than in the adjacent cropped field (3.67 and 2.12 mgNkg–1d−1 respectively). The DEA was significantly different between the two buffer strips under comparison, assessing that the management of the buffer strips has a dominant effect on DEA. The old unmown buffer strip is potentially more efficient in the nitrate removal process than the 6-year-old seeded buffer strip.
Arteriovenous Access for Hemodialysis
Authors: Lok Charmaine E. , Huber Thomas S. , Orchanian-Cheff Ani , Rajan Dheeraj K. 
Published: March 2024

ImportanceHemodialysis requires reliable vascular access to the patient’s blood circulation, such as an arteriovenous access in the form of an autogenous arteriovenous fistula or nonautogenous arteriovenous graft. This Review addresses key issues associated with the construction and maintenance of hemodialysis arteriovenous access.ObservationsAll patients with kidney failure should have an individualized strategy (known as Patient Life-Plan, Access Needs, or PLAN) for kidney replacement therapy and dialysis access, including contingency plans for access failure. Patients should be referred for hemodialysis access when their estimated glomerular filtration rate progressively decreases to 15 to 20 mL/min, or when their peritoneal dialysis, kidney transplant, or current vascular access is failing. Patients with chronic kidney disease should limit or avoid vascular procedures that may complicate future arteriovenous access, such as antecubital venipuncture or peripheral insertion of central catheters. Autogenous arteriovenous fistulas require 3 to 6 months to mature, whereas standard arteriovenous grafts can be used 2 to 4 weeks after being established, and “early-cannulation” grafts can be used within 24 to 72 hours of creation. The prime pathologic lesion of flow-related complications of arteriovenous access is intimal hyperplasia within the arteriovenous access that can lead to stenosis, maturation failure (33%-62% at 6 months), or poor patency (60%-63% at 2 years) and suboptimal dialysis. Nonflow complications such as access-related hand ischemia (“steal syndrome”; 1%-8% of patients) and arteriovenous access infection require timely identification and treatment. An arteriovenous access at high risk of hemorrhaging is a surgical emergency.Conclusions and RelevanceThe selection, creation, and maintenance of arteriovenous access for hemodialysis vascular access is critical for patients with kidney failure. Generalist clinicians play an important role in protecting current and future arteriovenous access; identifying arteriovenous access complications such as infection, steal syndrome, and high-output cardiac failure; and making timely referrals to facilitate arteriovenous access creation and treatment of arteriovenous access complications.
Differences in Care Team Response to Patient Portal Messages by Patient Race and Ethnicity
Authors: Tang Mitchell , Mishuris Rebecca G. , Payvandi Lily , Stern Ariel D. 
Published: March 2024

ImportanceThe COVID-19 pandemic was associated with substantial growth in patient portal messaging. Higher message volumes have largely persisted, reflecting a new normal. Prior work has documented lower message use by patients who belong to minoritized racial and ethnic groups, but research has not examined differences in care team response to messages. Both have substantial ramifications on resource allocation and care access under a new care paradigm with portal messaging as a central channel for patient–care team communication.ObjectiveTo examine differences in how care teams respond to patient portal messages sent by patients from different racial and ethnic groups.Design, Setting, and ParticipantsIn a cross-sectional design in a large safety-net health system, response outcomes from medical advice message threads sent from January 1, 2021, through November 24, 2021, from Asian, Black, Hispanic, and White patients were compared, controlling for patient and message thread characteristics. Asian, Black, Hispanic, and White patients with 1 or more adult primary care visits at Boston Medical Center in calendar year 2020 were included. Data analysis was conducted from June 23, 2022, through December 21, 2023.ExposurePatient race and ethnicity.Main Outcomes and MeasuresRates at which medical advice request messages were responded to by care teams and the types of health care professionals that responded.ResultsA total of 39 043 patients were included in the sample: 2006 were Asian, 21 600 were Black, 7185 were Hispanic, and 8252 were White. A total of 22 744 (58.3%) patients were women and mean (SD) age was 50.4 (16.7) years. In 2021, these patients initiated 57 704 medical advice request message threads. When patients who belong to minoritized racial and ethnic groups sent these messages, the likelihood of receiving any care team response was similar, but the types of health care professionals that responded differed. Black patients were 3.95 percentage points (pp) less likely (95% CI, −5.34 to −2.57 pp; P &amp;lt; .001) to receive a response from an attending physician, and 3.01 pp more likely (95% CI, 1.76-4.27 pp; P &amp;lt; .001) to receive a response from a registered nurse, corresponding to a 17.4% lower attending response rate. Similar, but smaller, differences were observed for Asian and Hispanic patients.Conclusions and RelevanceThe findings of this study suggest lower prioritization of patients who belong to minoritized racial and ethnic groups during triaging. Understanding and addressing these disparities will be important for improving care equity and informing health care delivery support algorithms.
Regulating the Electronic Synergy of Asymmetric Atomic Fe Sites with Adjacent Defects for Boosting Activity and Durability toward Oxygen Reduction
Authors: Ji Siqi , Wang Yuhao , Liu Hongxue , Lu Xue , Guo Chunmin , Xin Shixuan , Horton Joseph Hugh , Zhan Fei , Wang Yu , Li Zhijun 
Published: March 2024

AbstractThe oxygen reduction reaction (ORR) plays a fundamental role in sustainable energy technologies. However, the creation of non‐precious metal electrocatalysts with high ORR activity and durability under all pH conditions is of great significance but remains challenging. Herein, the aim is to overcome this challenge by creating a Fe single atom catalyst on a 2D defect‐containing nitrogen‐doped carbon support (Fe1/DNC) via a microenvironment engineering strategy. Microkinetic modeling reveals that FeN4(OH) moieties are the real active sites under reaction conditions. Due to the synergistic promotion effect of denser accessible FeN4(OH) moieties and defect‐induced electronic properties, Fe1/DNC catalyst achieves extraordinary ORR activity under alkaline, acidic, and neutral conditions, with half‐wave potentials of 0.95, 0.82, and 0.70 V, respectively. Moreover, a negligible performance decay is observed with this Fe catalyst in stability and methanol tolerance tests. Zn‐air battery employing Fe1/DNC delivers remarkable peak power density and long‐term operational durability. Theoretical analysis provides compelling evidence that the defects adjacent to FeN4(OH) moieties can endow an inductive effect to reshape electronic properties to balance the OOH* formation and OH* reduction. This work offers insight into the regulation of asymmetric coordination structure and electronic properties of metal sites for boosting electrocatalytic activity and stability.
Pre‐Oxidating and Pre‐Carbonizing to Regulate the Composition and Structure of Coal Tar Pitch: The Fabrication of Porous Carbon for Supercapacitor Applications
Authors: Liu Qian , Wu Dongling , Wang Tao , Wang Caige , Jia Dianzeng 
Published: March 2024

AbstractThe capacitive properties of supercapacitors highly rely on the reasonable design of high‐performance electrode materials. Herein, a synergetic strategy of pre‐oxidation and pre‐carbonization is proposed to prepare coal tar pitch (CTP) based porous carbon. The formation mechanism of porous carbon is revealed. Pre‐oxidation increases the heteroatom content and promotes the decomposition of polycyclic aromatic hydrocarbons into small molecules, which is more conducive to improving the subsequent activation and enhancing the microporous specific surface area. Also, the autoclave pre‐carbonization promotes the polymerization of the precursors and increases the carbon yield. Benefiting from the synergistic effect of pre‐oxidation and pre‐carbonation, the obtained carbon exhibits a superior specific capacitance of 365 F g−1. Meanwhile, ZnCl2 is used as a hydrogen‐bonding acceptor to synthesize ZnCl2‐EG/PVA deep eutectic solvent (DES) gel, and it is applicable to acidic, neutral, and alkaline electrolytes. The capacitor assembled with the prepared porous carbon and DES gel electrolyte achieves a high energy density of 41.3 Wh kg−1 and works well in unconventional temperatures (−40–75 °C). This work confirms the effect of pre‐oxidation and pre‐carbonization on the fabrication of CTP‐based carbon material and expects to prepare porous carbon using other pre‐oxidation/carbonization agents.
Transparent Composite Ceramic@aluminum with Ultra‐High Thermal Conductivity for High‐Brightness Laser‐Driven Lighting
Authors: Xi Guoyu , Zhou Zhenzhen , Li Jiang , Zeng Lingwei , Lin Shisheng , Wang Pengfei , Lin Hang , Wang Yuansheng , Zhou Su , Huang Feng , Chen Guilin , Chen Daqin 
Published: March 2024

AbstractNext‐generation high‐brightness lighting faces a big challenge in developing laser‐drivable color‐converting materials with effective thermal management. Herein, a new material architecture of Al2O3‐Y3Al5O12: Ce3+ (YAG: Ce) transparent composite ceramics coated with Al film (TCC@Al) is proposed. The as‐prepared material shows the highest thermal conductivity (29.3 W m−1 K−1) among YAG: Ce‐related transparent ceramics (TC) ever reported owing to the combination role of short‐range thermal conduction of Al2O3 microcrystals and long‐range thermal conduction of Al film. Temperature‐dependent photoluminescence (PL) spectra and femtosecond transient absorption (fs‐TA) spectra evidence the importance of thermal management, whereby the luminescent loss of TCC@Al is only 8.92% at 450 K and is far smaller than TC counterpart (15.86%). Importantly, no obvious luminescence saturation is detected upon 20 W mm−2 blue laser irradiation and the inhomogeneous angular color distribution is suppressed by the scatter of Al2O3 microcrystals, yielding uniform white light with ultra‐high luminous flux (LF) of 4294 lm@20 W mm−2 and luminous efficacy (LE) of 215 lm W−1. As a consequence, the present TCC@Al‐converted laser‐driven lighting prototype exhibits much better optical performance than the commercial TC‐based one.
Living Synthelectronics: A New Era for Bioelectronics Powered by Synthetic Biology
Authors: Sun Jing , Yang Ruofan , Li Qingsong , Zhu Runtao , Jiang Ying , Zang Lei , Zhang Zhibo , Tong Wei , Zhao Hang , Li Tengfei , Li Hanfei , Qi Dianpeng , Li Guanglin , Chen Xiaodong , Dai Zhuojun , Liu Zhiyuan 
Published: March 2024

AbstractBioelectronics, which converges biology and electronics, has attracted great attention due to their vital applications in human–machine interfaces. While traditional bioelectronic devices utilize nonliving organic and/or inorganic materials to achieve flexibility and stretchability, a biological mismatch is often encountered because human tissues are characterized not only by softness and stretchability but also by biodynamic and adaptive properties. Recently, a notable paradigm shift has emerged in bioelectronics, where living cells, and even viruses, modified via gene editing within synthetic biology, are used as core components in a new hybrid electronics paradigm. These devices are defined as “living synthelectronics,” and they offer enhanced potential for interfacing with human tissues at informational and substance exchange levels. In this Perspective, the recent advances in living synthelectronics are summarized. First, opportunities brought to electronics by synthetic biology are briefly introduced. Then, strategic approaches to designing and making electronic devices using living cells/viruses as the building blocks, sensing components, or power sources are reviewed. Finally, the challenges faced by living synthelectronics are raised. It is believed that this paradigm shift will significantly contribute to the real integration of bioelectronics with human tissues.