bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Unsteady Pressure Fluctuations in a Simplified Steam Turbine Control Valve
Authors: Windemuth Christian , Lange Martin , Mailach Ronald
Published: January 2021

Steam turbines are among the most important systems in commercial and industrial power conversion. As the amount of renewable energies increases, power plants formerly operated at steady-state base load are now experiencing increased times at part load conditions. Besides other methods, the use of control valves is a widely spread method for controlling the power output of a steam turbine. In difference to other throttling approaches, the control valve enables fast load gradients as the boiler can be operated at constant conditions and allows a quicker response on variable power requirements. At part load, a significant amount of energy is dissipated across the valve, as the total inlet pressure of the turbine is decreased across the valve. At these conditions, the flow through the valve becomes trans- and supersonic and large pressure fluctuations appear within the downstream part of the valve. As a result, unsteady forces are acting on the valve structure and vibrations can be triggered, leading to mechanical stresses and possible failures of the valve. Besides more complex valve geometries, a spherical valve shape is still often used in smaller and industrial steam turbines. Because of the smooth head contour, the flow is prone to remain attached to the head surface and interact with the flow coming from the opposite side. This behavior is accompanied by flow instabilities and large pressure fluctuations, leading to unsteady forces and possible couplings with mechanical frequencies. The spherical valve shape was therefore chosen as the experimental test geometry for the investigation of the unsteady flow field and fluid–structure interactions within a scaled steam turbine control valve. Using numerical methods, the test valve is investigated and the time dependent pressure distribution in the downstream diffuser is evaluated. The evolution of the flow stability will be discussed for different pressure ratios (PRs). Pressure signals retrieved from the control valve test rig will be used to compare the numerical results with the experimental data.
30 Years of Dry-Low-NOx Micromix Combustor Research for Hydrogen-Rich Fuels—An Overview of Past and Present Activities
Authors: Funke Harald H.-W. , Beckmann Nils , Keinz Jan , Horikawa Atsushi
Published: January 2021

This paper presents an overview of the past and present of low-emission combustor research with hydrogen-rich fuels at Aachen University of Applied Sciences (AcUAS). In 1990, AcUAS started developing the dry-low-NOx Micromix combustion technology. Micromix reduces NOx emissions using jet-in-crossflow mixing of multiple miniaturized fuel jets and combustor air with an inherent safety against flashback. At first, pure hydrogen as fuel was investigated with lab-scale applications. Later, Micromix combustor prototypes were developed for the use in an industrial gas turbine Honeywell/Garrett GTCP-36-300, proving low NOx characteristics during real gas turbine operation, accompanied by the successful definition of safety laws and control system modifications. Further, the Micromix was optimized for the use in annular and can-combustors as well as for fuel-flexibility with hydrogen-methane-mixtures and hydrogen-rich syngas qualities by means of extensive experimental and numerical simulations. In 2020, the latest Micromix application is demonstrated in a commercial 2 MW-class gas turbine can-combustor with full-scale engine operation. This paper discusses the advances in Micromix research over the last three decades.
Hybrid Numerical-Experimental Model Update Based on Correlation Approach for Turbine Components
Authors: Saeed Zeeshan , Firrone Christian Maria , Berruti Teresa Maria
Published: January 2021

Bladed-disks in turbomachines experience high cycle fatigue failures due to high vibration amplitudes. Therefore, it is important to accurately predict their dynamic characteristics including the mechanical joints at blade-disk interfaces. Before the experimental identification of these joints, it is of paramount importance to accurately measure the interface degrees-of-freedom (DoF). However, they are largely inaccessible for the measurements. For this reason, expansion techniques can be used in order to update the single components. But the expansion can be affected adversely if the measurements are not properly correlated with the updated model. Therefore, a frequency domain expansion method called System Equivalent Model Mixing (SEMM) is used to expand a limited set of measurements to a larger set of numerical DoF. Different measured models—termed the overlay models—are taken from an impact testing campaign of a blade and a disk and coupled to the numerical model according to the SEMM. The expanded models—termed the hybrid models—are then correlated with the validation channels in a round-robin way by means of Frequency Response Assurance Criteria (FRAC). The global correlations depict whether or not a measurement and the respective expansion is properly correlated. By this approach, the least correlated channels can be eliminated from the measurements to have a better updated hybrid model. The method is tested on both the structures (the blade and the disk) and it is successfully shown that removing the uncorrelated channels does improve the quality of the hybrid models.
Water Droplet Erosion Life Prediction Method for Steam Turbine Blade Materials Based on Image Recognition and Machine Learning
Authors: Zhang Zheyuan , Liu Tianyuan , Zhang Di , Xie Yonghui
Published: January 2021

In this paper, a method for predicting remaining useful life (RUL) of turbine blade under water droplet erosion (WDE) based on image recognition and machine learning is presented. Using the experimental rig for testing the WDE characteristics of materials, the morphology pictures of specimen surface at different times in the process of WDE are collected. According to the data processing method of ASTM-G73 and the cumulative erosion-time curves, the WDE stages of materials is quantitatively divided and the WDE life coefficient (ζ) is defined. The life coefficient (ζ) could be used to calculate the RUL of turbine blades. One convolutional neural network model and three machine learning models are adopted to train and predict the image dataset. Then the training process and feature maps of the Resnet model are studied in detail. It is found that the highest prediction accuracy of the method proposed in this paper can be 0.949, which is considered acceptable to provide reference for turbine overhaul period and blade replacement time.
Thermo-Economic Assessment Under Electrical Market Uncertainties of a Combined Cycle Gas Turbine Integrated With a Flue Gas-Condensing Heat Pump
Authors: Vannoni Alberto , Giugno Andrea , Sorce Alessandro
Published: January 2021

Renewable energy penetration is growing, due to the target of greenhouse-gas-emission reduction, even though fossil fuel-based technologies are still necessary in the current energy market scenario to provide reliable back-up power to stabilize the grid. Nevertheless, currently, an investment in such a kind of power plant might not be profitable enough, since some energy policies have led to a general decrease of both the average single national price of electricity (PUN) and its variability; moreover, in several countries, negative prices are reached on some sunny or windy days. Within this context, combined heat and power (CHP) systems appear not just as a fuel-efficient way to fulfill local thermal demand but also as a sustainable way to maintain installed capacity able to support electricity grid reliability. Innovative solutions to increase both the efficiency and flexibility of those power plants, as well as careful evaluations of the economic context, are essential to ensure the sustainability of the economic investment in a fast-paced changing energy field. This study aims to evaluate the economic viability and environmental impact of an integrated solution of a cogenerative combined cycle gas turbine power plant with a flue gas condensing heat pump. Considering capital expenditure, heat demand, electricity price, and its fluctuations during the whole system life, the sustainability of the investment is evaluated taking into account the uncertainties of economic scenarios and benchmarked against the integration of a cogenerative combined cycle gas turbine power plant with a heat-only boiler (HOB).
Experimental Analysis of Surge-Detection System Based on Pressure Derivatives at Part-Speed Operation
Authors: Liskiewicz Grzegorz , Kabalyk Kirill , Jaeschke Andrzej , Grapow Filip , Kulak Michał , Kryłłowicz Władysław , Ouyang Hua , Shen Xin
Published: January 2021

This paper presents tests of an antisurge system based on pressure derivatives. The control algorithm was proven to work on different machines and with different unstable flow phenomena. Compressors are known to be affected by unstable flow conditions appearing at low mass flowrate conditions. The best known and most dangerous phenomenon is surge, which is a global instability affecting the entire impeller and regions upstream and downstream from it. A list of identified local phenomena includes among others: impeller rotating stall, diffuser rotating stall, and inlet recirculation. All have a specific pressure signature that is used for early identification. The method presented in this paper is based on a control parameter named the rate of derivative fluctuation (RDF). This approach involves a simple measure of flow instability that is universal and reacts to flow disturbances. RDF has been already confirmed to identify inlet recirculation and surge. The aim of this study is to conduct real-time tests of an antisurge system, implementing the RDF algorithm triggering the safety valve opening. The study confirmed the optimal position of the monitoring point. The results showed that the RDF is indeed sensitive to different types of flow instabilities appearing in different impellers, and that it provides efficient flow stability monitoring.
Experimental and Numerical Assessment of Mistuning Effects on Vibratory Response of a Bladed Disk With Underplatform Dampers
Authors: Mehrdad Pourkiaee S. , Berruti Teresa , Zucca Stefano , Neuville Geoffrey
Published: January 2021

This paper presents experimental and numerical investigation of mistuned forced responses of an integrally bladed disk with full set of underplatform dampers (UPDs). This research aims at providing: 1. An experimental benchmark for nonlinear dynamics of a mistuned bladed disks with UPDs. 2. A numerical model that can account for features of a mistuned forced response level. Accordingly, a detailed experimental campaign is conducted on a static test rig called Octopus. This rig is specifically designed to investigate the dynamics of a full-scale integrally bladed disk (blisk) with UPDs in a noncontact manner so that the dynamic response of the system is not modified. The effect of mistuning on experimental forced response levels is assessed and a linearized model is proposed to predict the modulation of frequency response functions (FRFs) due to the frequency splitting. In the development of the model, the mistuning pattern identified from the linear blisk without UPDs is used and it is assumed that adding the dampers does not change the structural mistuning of the blisk. In this study, the fundamental mistuning model identification (FMM ID) was employed to identify the mistuning pattern of the blisk. It is shown that the proposed model successfully predicts the modulation of linear mistuned FRFs. The linearized model is also able to predict the modulation of nonlinear mistuned FRFs in stick condition (when nonlinear friction damping is negligible) with a good accuracy validating this assumption that adding the dampers does not change the mistuning pattern.
Test Results for the Static and Rotordynamic Characteristics of a Long (L/D = 0.75) Smooth Seal in Two-Phase (Mainly Gas) Conditions With a 62-Bar Inlet Pressure
Authors: Tran Dung L. , Childs Dara W. , Shrestha Hari , Zhang Min
Published: January 2021

Recent multiphase-pump developments encountered several rotordynamic issues with smooth balance-piston seals, creating a need to better understand the performance of annular seals under multiphase-flow operation. This paper presents measurements of static and dynamic characteristics of a long smooth seal (L/D = 0.75, D = 114.686 mm, and Cr = 0.200 mm) operating under pure- and mainly air condition in which air is mixed with silicone oil (PSF-5cSt). Tests are performed at a supply pressure of 62.1 bars-g, three rotation speeds (5, 10, and 15 krpm), three pressure ratios (PRs) (0.6, 0.5, 0.4), for a range of inlet liquid volume fraction (LVFi) from 0% to 8%. The results are then compared to: (1) the previous test reported by Zhang et al. (2017, “Experimental Study of the Static and Dynamic Characteristics of a Long Smooth Seal with Two-Phase, Mainly-air Mixtures,” ASME J. Eng. Gas Turbines Power, 139(12), p. 122504) with similar testing condition but a different seal geometry (L/D = 0.65, D = 89.306 mm, and Cr = 0.188 mm) and (2) the predictions from a bulk-flow model developed by San Andrés (2012, “Rotordynamic Force Coefficients of Bubbly Mixture Annular Pressure Seals,” ASME J. Eng. Gas Turbines Power, 134(2), p. 022503). Results show a significant increase of direct dynamic stiffness KΩ as LVFi increases, especially at low PR. Test results reported by Zhang et al. (2017, “Experimental Study of the Static and Dynamic Characteristics of a Long Smooth Seal with Two-Phase, Mainly-air Mixtures,” ASME J. Eng. Gas Turbines Power, 139(12), p. 122504) has an opposite tendency of KΩ as an impact of increasing LVFi values. Concerning cross-coupled dynamic stiffness kΩ and cross-coupled damping c, the results from Zhang et al. (2017) and the present results agree to the effects of changing speed, PR, and LVFi under pure- and mainly air conditions. As LVFi increases, direct damping C increases while test results reported by Zhang et al. (2017, “Experimental Study of the Static and Dynamic Characteristics of a Long Smooth Seal with Two-Phase, Mainly-air Mixtures,” ASME J. Eng. Gas Turbines Power, 139(12), p. 122504) showed no significant increase. A steady-state computational fluid dynamics (CFD) result for a testing case suggests a significant difference happening inside the two seals (present seal and Zhang et al.'s (2017, “Experimental Study of the Static and Dynamic Characteristics of a Long Smooth Seal with Two-Phase, Mainly-air Mixtures,” ASME J. Eng. Gas Turbines Power, 139(12), p. 122504) seal). A full investigation in CFD is needed. Except for the direct dynamic stiffness and the impact of changing LVFi on the cross-coupled dynamic stiffness, the bulk-flow model of San Andrés (2012, “Rotordynamic Force Coefficients of Bubbly Mixture Annular Pressure Seals,” ASME J. Eng. Gas Turbines Power, 134(2), p. 022503) predicts decently the tendencies and magnitudes of the rotordynamic coefficients.
Heavy Fuel Oil Combustion Characteristics Evaluation in Various Swirling Flow Conditions
Authors: Pei Xinyan , Elbaz A.M. , Jiang Long , AlAhmadi Kamal M. , Saxena Saumitra , Roberts William L.
Published: January 2021

Heavy fuel oil (HFO) is an economical fuel alternative for power generation as its low production cost and high energy density. However, its incomplete combustion induced by the presence of long-chain petroleum molecules in the fuel results in high levels of emissions. Here, we investigate the influence of the swirl flow on the combustion and emissions of a spray HFO swirling flame. To this end, HFO is sprayed into a hot swirling air, using an air-blast nozzle. The flame blowout limits are tested under different swirl flows. An investigation of the in-flame temperature fields, gaseous emissions including CO, CO2, O2, NOx, SOx, UHC (Unburned Hydrocarbon) and solid particles in the form of cenospheres are used to quantify the performance of the HFO combustion. The influence of the HFO swirling flame is tested under different conditions of global equivalence ratio, swirling number, and tangential and axial airflow rates. A comparison of two different flame regimes that fuel-jet dominate flame and air-driven vortex flows are investigated and compared in various swirling flow conditions. The results show that the tangent air is the primary factor for preheating and evaporating the fuel, thus defining the flame operating regimes.
Thermodynamic Investigation of an Irreversible Combined Stirling-Organic Rankine Cycle for Maximum Power Output Condition
Authors: Ramachandran Siddharth , Kumar Naveen , Timmaraju Mallina Venkata
Published: January 2021

A pragmatic approach is adopted to investigate irreversible thermodynamic combined cycle devices. The finite-time thermodynamic model of combined Stirling-organic Rankine cycle is formulated and evaluated for maximum output power and thermal efficiency. The influence of effectiveness of heat exchangers, heat capacitance of external fluids, and inlet temperatures of heat exchangers at heat source, heat recovery unit and heat sink on the performance of Stirling-organic Rankine cycle are investigated to get their corresponding optimum. The maximum allowable heat capacitance of external fluids of heat source and heat recovery units are about 1.1 kW/K and 1.4 kW/K, respectively, for the operating conditions considered in the present study. The maximum power output is achieved only when the effectiveness of heat exchangers is ideal. The overall performance of Stirling-organic Rankine cycle combination will be higher than either of the performances of individual cycles provided that the isothermal heat rejection from Stirling cycle takes place at temperature above 540 K. Further, a 0.2 increase in the internal irreversibility parameter from an ideal/reversible condition reduced the maximum output power and the corresponding thermal efficiency of Stirling-organic Rankine cycle by 16.1 kW and 24%, respectively.
Design of Stress Constrained SiC/SiC Ceramic Matrix Composite Turbine Blades
Authors: Boyle Robert J. , Gnanaselvam Pritheesh , Parikh Ankur H. , Ameri Ali A. , Bons Jeffrey P. , Nagpal Vinod K.
Published: January 2021

The structural and aerodynamic performance of a low aspect ratio SiC/SiC ceramic matrix composite (CMC) high pressure turbine (HPT) blade was determined. The application was a NASA notional single aisle aircraft engine to be available in the N + 3, beyond 2030, time frame. The notional rpm was maintained, and to satisfy stress constraints, the annulus area was constrained. This led to a low span blade. For a given clearance, low span blade is likely to have improved efficiency when shrouded. The efficiency improvement due to shrouding was found to strongly depend on the axial gap between the shroud and casing. Axial gap, unlike clearance or reaction, is not a common parameter used to correlate the efficiency improvement due to shrouding. The zero clearance stage efficiency of the low aspect ratio turbine was 0.920. Structural analyses showed that the rotor blade could be shrouded without excessive stresses. The goal was to have blade stresses less than 100 MPa (14.5 ksi) for the unshrouded blade. Under some not very restrictive circumstances, such as blade stacking, a one-dimensional radial stress equation accurately predicted area averaged Von Mises stress at the blade hub. With appropriate stacking, radial and Von Mises stresses were similar.
Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine-Relevant Conditions
Authors: Ebi Dominik , Jansohn Peter
Published: January 2021

Operating stationary gas turbines on hydrogen-rich fuels offers a pathway to significantly reduce greenhouse gas emissions in the power generation sector. A key challenge in the design of lean-premixed burners, which are flexible in terms of the amount of hydrogen in the fuel across a wide range and still adhere to the required emission levels, is to prevent flame flashback. However, systematic investigations on flashback at gas turbine relevant conditions to support combustor development are sparse. The current work addresses the need for an improved understanding with an experimental study on boundary layer flashback in a generic swirl burner up to 7.5 bar and 300 °C preheat temperature. Methane-hydrogen-air flames with 50 to 85% hydrogen by volume were investigated. High-speed imaging was applied to reveal the flame propagation pathway during flashback events. Flashback limits are reported in terms of the equivalence ratio for a given pressure, preheat temperature, bulk flow velocity, and hydrogen content. The wall temperature of the center body along which the flame propagated during flashback events has been controlled by an oil heating/cooling system. This way, the effect any of the control parameters, e.g., pressure, had on the flashback limit was decoupled from the otherwise inherently associated change in heat load on the wall and thus change in wall temperature. The results show that the preheat temperature has a weaker effect on the flashback propensity than expected. Increasing the pressure from atmospheric conditions to 2.5 bar strongly increases the flashback risk, but hardly affects the flashback limit beyond 2.5 bar.
Estimating the impact of tax policy interventions on the projected number and prevalence of adults with type 2 diabetes in Germany between 2020 and 2040
Authors: Tönnies Thaddäus , Heidemann Christin , Paprott Rebecca , Seidel-Jacobs Esther , Scheidt-Nave Christa , Brinks Ralph , Hoyer Annika
Published: January 2021

Introduction

As a population-wide intervention, it has been proposed to raise taxes on unhealthy products to prevent diseases such as type 2 diabetes. In this study, we aimed to estimate the effect of tax policy interventions in 2020 on the projected prevalence and number of people with type 2 diabetes in the German adult population in 2040.

Research design and methods

We applied an illness-death model and the German Diabetes Risk Score (GDRS) to project the prevalence and number of adults with type 2 diabetes in Germany under a base case scenario and under a tax policy intervention scenario. For the base case scenario, we assumed constant age-specific incidence rates between 2020 and 2040. For the intervention scenario, we assumed a 50% price increase for sugar-sweetened beverages, tobacco and red meat products in the year 2020. Based on price elasticities, we estimated the impact on these risk factors alone and in combination, and calculated subsequent reductions in the age-specific and sex-specific GDRS. These reductions were used to determine reductions in the incidence rate and prevalence using a partial differential equation.

Results

Compared with the base case scenario, combined tax interventions in 2020 resulted in a 0.95 percentage point decrease in the prevalence of type 2 diabetes (16.2% vs 17.1%), which corresponds to 640 000 fewer prevalent cases of type 2 diabetes and a relative reduction by 6%.

Conclusions

Taxation of sugar-sweetened beverages, tobacco products and red meat by 50% modestly lowered the projected number and prevalence of adults with type 2 diabetes in Germany in 2040. Raising taxes on unhealthy products as a stand-alone measure may not be enough to attenuate the future rise of type 2 diabetes.
Atherogenic dyslipidaemia and cardiovascular events in patients with diabetes or pre-diabetes and stable coronary artery disease: a prospective, cohort study
Authors: Jin Jing-Lu , Cao Ye-Xuan , Wu Li-Guo , You Xiang-Dong , Guo Na , Guo Yuan-Lin , Wu Na-Qiong , Zhu Cheng-Gang , Xu Rui-Xia , Liu Hui-Hui , Sun Jing , Dong Qian , Gao Ying , Li Jian-Jun
Published: January 2021

Objective

The aim of the study was to investigate the impacts of triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) dyslipidaemia on prognosis in coronary artery disease (CAD) patients with different glucose metabolism status.

Design

An observational cohort study.

Setting/participants

A total of 3057 patients with stable CAD were consecutively enrolled and divided into three groups according to different glucose metabolism status. Atherogenic dyslipidaemia (AD) was defined as TG ≥1.7 mmol/L and HDL-C <1.0 mmol/L for men or <1.3 mmol/L for women. The patients were further classified into six subgroups by status of AD. All subjects were followed up for the cardiovascular events (CVEs).

Primary outcome measures

The primary endpoints were cardiovascular mortality, non-fatal myocardial infarction and non-fatal stroke.

Results

During a median follow-up of 6.1 years, 308 (10.1%) CVEs occurred. No significant difference in the occurrence of CVEs was observed between normal glucose regulation (NGR) and pre-diabetes (pre-DM) groups (HR: 1.25, 95% CI 0.89 to 1.76) while DM group presented 1.45-fold higher risk of CVEs (HR: 1.45, 95% CI 1.02 to 2.05). When the participants were categorised according to combined status of two parameters, the cardiovascular risk was significantly elevated in pre-DM or DM plus AD group compared with the NGR plus non-AD group (HR: 1.76, 95% CI 1.10 to 2.80 and HR: 1.87, 95% CI 1.17 to 2.98).

Conclusions

The present study suggested that the presence of AD might affect the prognosis in patients with DM or pre-DM and stable CAD.
Prevalence and associated factors of depression among adolescent boys and girls in Bangladesh: findings from a nationwide survey
Authors: Mridha Malay Kanti , Hossain Md Mokbul , Khan Md Showkat Ali , Hanif Abu Abdullah Mohammad , Hasan Mehedi , Mitra Dipak , Hossaine Moyazzam , Ullah Mohammad Aman , Sarker Samir Kanti , Rahman S M Mustafizur , Bulbul Md M Islam , Shamim Abu Ahmed
Published: January 2021

Objective

To assess the prevalence of and factors associated with depression among adolescent boys and girls.

Design

We conducted a nationwide cross-sectional study.

Setting

This study was carried out in 82 randomly selected clusters (57 rural, 15 non-slum urban and 10 slums) from eight divisions of Bangladesh.

Participants

We interviewed 4907 adolescent boys and 4949 adolescent girls.

Primary and secondary outcome measures

The primary outcome measure was ‘any depression’ and the secondary outcome measures were types of depression: no or minimal, mild, moderate, moderately severe and severe.

Results

The overall prevalence of no or minimal, mild, moderate, moderately severe and severe depression was 75.5%, 17.9%, 5,4%, 1.1% and 0.1%, respectively. Across most of the sociodemographic, lifestyle and anthropometric strata, the prevalence of any depression was higher among adolescent girls. In both sexes, depression was associated with higher age, higher maternal education, paternal occupation e.g., business, absence of a 6–9-year-old member in the household, food insecurity, household consumption of unfortified oil, household use of non-iodised salt, insufficient physical activity (adjusted odds ratio, AOR: 1.24 for boys, 1.44 for girls) and increased television viewing time e.g., ≥121 minute/day (AOR: 1.95 for boys, 1.99 for girls). Only among boys, depression was also associated with higher paternal education e.g., complete secondary and above (AOR: 1.42), absence of another adolescent member in the household (AOR: 1.34), household use of solid biomass fuel (AOR: 1.39), use of any tobacco products (AOR: 2.17), and consumption of processed food (AOR: 1.24). Only among girls, non-slum urban residence, Muslim religion, and household size ≤4 were also associated with depression.

Conclusion

The prevalence of depression among adolescent boys and girls is high in Bangladesh. In most sociodemographic, lifestyle and anthropometric strata, the prevalence is higher among girls. In this age group, depression is associated with a number of sociodemographic and lyfestyle factors. The government of Bangladesh should consider these findings while integrating adolescent mental health in the existing and future programmes.
Construction of the National Brain Tumor Registry of China for better management and more efficient use of data: a protocol
Authors: Zhang Liwei , Jia Wang , Ji Nan , Li Deling , Xiao Dan , Shan Guang-Liang , Wang Tao , Xiao Xiong
Published: January 2021

Introduction

Brain tumours encompass a complex group of intracranial tumours that mostly affect young adults and children, with a high incidence rate and poor prognosis. It remains impossible to systematically collect data on patients with brain tumours in China and difficult to perform in-depth analysis on the status of brain tumours, medical outcomes or other important medical issues through a multicentre clinical study. This study describes the first nation-wide data platform including the entire spectrum of brain tumour entities, which will allow better management and more efficient application of patient data in China.

Methods and analysis

The National Brain Tumor Registry of China (NBTRC) is a registry of real-word clinical data on brain tumours. It is established and managed by the China National Clinical Research Center for Neurological Diseases and administered by its scientific and executive committees. The 54 participating hospitals of the NBTRC are located in 27 provinces/municipalities, performing more than 40 000 brain tumour surgeries per year. The data consist of in-hospital medical records, images and follow-up information after discharge. Data can be uploaded in three ways: the web portal, remote physical servers and offline software. The data quality control scheme is seven-dimensional. Each participating hospital could focus on a single pathology subtype and public subtypes of brain tumour for which they expect to conduct related multicentre clinical research. The standardised workflow to conduct clinical research is based on the benefit-sharing mechanism. Data collection will be conducted continuously from 1 February 2019 to 31 January 2024.

Ethics and dissemination

Informed consent will be obtained from all participants. Consent for the adolescents’ participation will be also obtained from their guardians via written consent. The results will be published in professional journals, in both Chinese and English.

Trial registration number

Chinese Clinical Trial Registry (ChiCTR1900021096).
Development and temporal external validation of a simple risk score tool for prediction of outcomes after severe head injury based on admission characteristics from level-1 trauma centre of India using retrospectively collected data
Authors: Kamal Vineet Kumar , Pandey Ravindra Mohan , Agrawal Deepak
Published: January 2021

Objective

To develop and validate a simple risk scores chart to estimate the probability of poor outcomes in patients with severe head injury (HI).

Design

Retrospective.

Setting

Level-1, government-funded trauma centre, India.

Participants

Patients with severe HI admitted to the neurosurgery intensive care unit during 19 May 2010–31 December 2011 (n=946) for the model development and further, data from same centre with same inclusion criteria from 1 January 2012 to 31 July 2012 (n=284) for the external validation of the model.

Outcome(s)

In-hospital mortality and unfavourable outcome at 6 months.

Results

A total of 39.5% and 70.7% had in-hospital mortality and unfavourable outcome, respectively, in the development data set. The multivariable logistic regression analysis of routinely collected admission characteristics revealed that for in-hospital mortality, age (51–60, >60 years), motor score (1, 2, 4), pupillary reactivity (none), presence of hypotension, basal cistern effaced, traumatic subarachnoid haemorrhage/intraventricular haematoma and for unfavourable outcome, age (41–50, 51–60, >60 years), motor score (1–4), pupillary reactivity (none, one), unequal limb movement, presence of hypotension were the independent predictors as its 95% confidence interval (CI) of odds ratio (OR)_did not contain one. The discriminative ability (area under the receiver operating characteristic curve (95% CI)) of the score chart for in-hospital mortality and 6 months outcome was excellent in the development data set (0.890 (0.867 to 912) and 0.894 (0.869 to 0.918), respectively), internal validation data set using bootstrap resampling method (0.889 (0.867 to 909) and 0.893 (0.867 to 0.915), respectively) and external validation data set (0.871 (0.825 to 916) and 0.887 (0.842 to 0.932), respectively). Calibration showed good agreement between observed outcome rates and predicted risks in development and external validation data set (p>0.05).

Conclusion

For clinical decision making, we can use of these score charts in predicting outcomes in new patients with severe HI in India and similar settings.
Participatory health through behavioural engagement and disruptive digital technology for postoperative rehabilitation: protocol of the PATHway trial
Authors: Wang Xia , Hunter David J , Robbins Sarah , Capistrano Sarah , Duong Vicky , Melo Luciano , Harris Anthony , Ferreira Manuela
Published: January 2021

Introduction

Postsurgical rehabilitation is critical for optimal recovery in people undergoing orthopaedic surgery. Currently, knee and lumbar spine postsurgical care is not standardised, economically sustainable, nor based on quality evidence, contributing to substantial clinical variation, poor outcomes and increasing healthcare costs. This protocol describes the design of a randomised controlled trial aiming to evaluate the effectiveness and cost-effectiveness of a postsurgical clinical pathway augmented by disruptive technology and compared with standardised rehabilitation alone, in decreasing pain and improving function after total knee replacement (TKR) or lumbar laminectomy (with or without fusion).

Methods

An assessor-blinded, parallel group, randomised controlled trial will be conducted to recruit 204 consenting participants (102 per arm) of whom 50% are undergoing TKR and 50% lumbar surgery. The intervention group will receive a 6-month technology-enabled rehabilitation package in addition to usual postsurgical care. The package includes (1) an exercise program delivered via the Physitrack app on the iPad, (2) a health-coaching program delivered via video calls and motivational messages, (3) use of physical activity tracker with goal setting and motivational reminders (Fitbit). For those undergoing TKR, the intervention will also include knee joint range of motion self-monitoring via the Goniometer app. The control group will receive usual postsurgical care. Participants will be followed up at 3, 6 and 12 months from the enrolment date. The primary outcome is pain measured with the Numerical Rating Scale at 3 months. Secondary outcomes include pain-related disability, quality of life, computer self-efficacy, physical activity participation and sedentary behaviour. Data analysis will be blinded and by intention-to-treat. A trial-based cost-effectiveness analysis will determine the potential incremental cost per quality-adjusted life-year gained.

Ethics and dissemination

This protocol is approved by the human research ethics committee of the University of Sydney. Dissemination will occur through lay summary, infographics, conferences and journal publications.

Trial registration number

ACTRN12618001448235.
Probability of receiving a high cumulative radiation dose and primary clinical indication of CT examinations: a 5-year observational cohort study
Authors: Jeukens Cécile R L P N , Boere Hub , Wagemans Bart A J M , Nelemans Patty J , Nijssen Estelle C , Smith-Bindman Rebecca , Wildberger Joachim E , Sailer Anna M
Published: January 2021

Objective

High radiation exposure is a concern because of the association with cancer. The objective was to determine the probability of receiving a high radiation dose from CT (from one or more examinations within a 5-year period) and to assess the clinical context by evaluating clinical indications in the high-dose patient group.

Design

Observational cohort study. Effective radiation dose received from one or more CT examinations within a predefined 5-year calendar period was assessed for each patient.

Setting

Hospital setting.

Participants

All patients undergoing a diagnostic CT examination between July 2013 and July 2018 at the Maastricht University Medical Center.

Primary and secondary outcome measures

The primary outcome was the probability of receiving a high effective dose, defined as ≥100 mSv, from one or more CT examinations within 5 years as derived from a time-to-event analysis. Secondary outcomes were the clinical indication for the initial scan of patients receiving a high effective dose.

Results

100 672 CT examinations were performed among 49 978 patients including 482 (1%) who received a high radiation dose. The estimated probability of a high effective dose from a single examination is low (0.002% (95% CI 0.00% to 0.01%)). The 4.5-year probability of receiving a high cumulative effective dose was 1.9% (95% CI 1.6% to 2.2%) for women and 1.5% (95% CI 1.3% to 1.7%) for men. The probability was highest in age categories between 51 and 74 years. A total of 2711 (5.5%) of patients underwent more than six CT examinations, and the probability of receiving a high effective dose was 16%. Among patients who received a high effective dose, most indications (80%) were oncology related.

Conclusions

The probability of receiving a high radiation dose from CT examinations is small but not negligible. In the majority (80%) of high effective dose receiving patients, the indication for the initial CT scan was oncology related.
Acupuncture for biliary colic: a systematic review protocol
Authors: Sun Ning , Zuo Wenwei , Zhou Yuanfang , Cheng Ying , Cheng Shirui , Zhou Jun , Xu Guixing , Huang Liuyang , Liang Fanrong , Sun Ruirui
Published: January 2021

Introduction

Biliary colic (BC) is a severe pain associated with nausea and vomiting, which is the most common symptom among the gallstone population. This protocol proposes a methodology for conducting a systematic review and meta-analysis that aims to assess the benefits and safety of acupuncture in patients with BC.

Methods and analysis

Clinical trials will be identified through nine databases from inception to December 2020, using Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Allied and Complementary Medicine Database (AMED), CINAHL, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM), VIP Database and Wanfang Database. Search words will be used for the BC and acupuncture. The analysis would include randomised, controlled, clinical trials of adults with BC that were published in either Chinese or English. The primary outcome is to measure pain relief. Two or three reviewers should be in charge of study selection, data extraction and evaluating the risk of bias. RevMan software (V.5.4) will be used to perform the assessment of the risk of bias and data synthesis.

Ethics and dissemination

Ethics approval will not be required for this review, as it will only involve the collection of literature previously published. The results of this meta-analysis will be disseminated in a peer-reviewed journal or relevant conference, through publication.

Trial registration number

CRD42020167510.
Systematic approach to school-based assessments for autism spectrum disorders to reduce inequalities: a feasibility study in 10 primary schools
Authors: Wright Barry , Konstantopoulou Kalliopi , Sohal Kuldeep , Kelly Brian , Morgan Geoff , Hulin Cathy , Mansoor Sara , Mon-Williams Mark
Published: January 2021

Objectives

This was a pilot study to explore whether the Early Years Foundation Stage Profile (EYFSP) carried out by UK teachers within the ‘reception’ year, combined with the Social Communication Questionnaire (SCQ), can lead to early identification of children with autism spectrum disorders (ASD) and early access to intervention and can reduce inequity in access to assessment and intervention.

Design

Pragmatic prospective cohort.

Setting

Ten primary schools from the SHINE project in Bradford.

Participants

587 pupils from 10 schools who transitioned from reception to year 1 in July 2017 and had the EYFSP completed were included in the final study.

Interventions

The assessment involved a multidisciplinary team of three staff who completed Autism Diagnostic Interview–Revised, Autism Diagnostic Observation Schedule Version 2, classroom observations with an ASD checklist, a teacher-based ASD questionnaire and a final consensus meeting.

Primary outcome measure

National Institute for Health and Care Excellence guideline-compliant clinical diagnosis of ASD.

Secondary outcome measures

Age of diagnosis, demographic data and feasibility parameters.

Results

Children with low scores on the EYFSP were more likely to score above the SCQ threshold of 12, indicating potential autism (50% compared with 19% of children with high scores on the EYFSP (p<0.001)). All children scoring above the SCQ threshold received a full autism assessment; children who scored low on the EYFSP were more likely to be diagnosed with autism (and other developmental issues) compared with those who did not.

Conclusions

We identified nine new children with a diagnosis of ASD, all from ethnic minorities, suggesting that this process may be addressing the inequalities in early diagnosis found in previous studies. All children who scored above the SCQ threshold required support (ie, had a neurodevelopmental disorder), indicating the EYFSP questionnaire captured ‘at-risk’ children.
Ethnicity and outcomes in patients hospitalised with COVID-19 infection in East London: an observational cohort study
Authors: Apea Vanessa J , Wan Yize I , Dhairyawan Rageshri , Puthucheary Zudin A , Pearse Rupert M , Orkin Chloe M , Prowle John R
Published: January 2021

Objective

To describe outcomes within different ethnic groups of a cohort of hospitalised patients with confirmed COVID-19 infection. To quantify and describe the impact of a number of prognostic factors, including frailty and inflammatory markers.

Setting

Five acute National Health Service Hospitals in east London.

Design

Prospectively defined observational study using registry data.

Participants

1737 patients aged 16 years or over admitted to hospital with confirmed COVID-19 infection between 1 January and 13 May 2020.

Main outcome measures

The primary outcome was 30-day mortality from time of first hospital admission with COVID-19 diagnosis during or prior to admission. Secondary outcomes were 90-day mortality, intensive care unit (ICU) admission, ICU and hospital length of stay and type and duration of organ support. Multivariable survival analyses were adjusted for potential confounders.

Results

1737 were included in our analysis of whom 511 had died by day 30 (29%). 538 (31%) were from Asian, 340 (20%) black and 707 (40%) white backgrounds. Compared with white patients, those from minority ethnic backgrounds were younger, with differing comorbidity profiles and less frailty. Asian and black patients were more likely to be admitted to ICU and to receive invasive ventilation (OR 1.54, (95% CI 1.06 to 2.23); p=0.023 and OR 1.80 (95% CI 1.20 to 2.71); p=0.005, respectively). After adjustment for age and sex, patients from Asian (HR 1.49 (95% CI 1.19 to 1.86); p<0.001) and black (HR 1.30 (95% CI 1.02 to 1.65); p=0.036) backgrounds were more likely to die. These findings persisted across a range of risk factor-adjusted analyses accounting for major comorbidities, obesity, smoking, frailty and ABO blood group.

Conclusions

Patients from Asian and black backgrounds had higher mortality from COVID-19 infection despite controlling for all previously identified confounders and frailty. Higher rates of invasive ventilation indicate greater acute disease severity. Our analyses suggest that patients of Asian and black backgrounds suffered disproportionate rates of premature death from COVID-19.
Public’s understanding of swab test results for SARS-CoV-2: an online behavioural experiment during the April 2020 lockdown
Authors: Pighin Stefania , Tentori Katya
Published: January 2021

Objective

Although widespread testing for SARS-CoV-2 is in place, little is known about how well the public understands these results. We aimed to provide a comprehensive overview of the general public’s grasp of the accuracy and significance of the results of the swab test.

Design

Web-based behavioural experiment.

Setting

Italy during the April 2020 lockdown.

Participants

566 Italian residents.

Main outcome measures

Participants’ estimates of the SARS-CoV-2 prevalence; the predictive and diagnostic accuracy of the test; the behavioural impact of (positive vs negative) test results; the perceived usefulness of a short-term repetition of the test following positive or negative results; and rankings of causes for false positives and false negatives.

Results

Most participants considered the swab test useful (89.6%) and provided predictive values consistent with their estimates of test diagnostic accuracy and infection prevalence (67.0%). Participants acknowledged the effects of symptomatic status and geographical location on prevalence (all p<0.001) but failed to take this information into account when estimating the positive or negative predictive value. Overall, test specificity was underestimated (91.5%, 95% CI 90.2% to 92.8%); test sensitivity was overestimated (89.7%, 95% CI 88.3% to 91.0%). Positive results were evaluated as more informative than negative ones (91.6, 95% CI 90.2 to 93.1 and 41.0, 95% CI 37.9 to 44.0, respectively, p<0.001); a short-term repetition of the test was considered more useful after a positive than a negative result (62.7, 95% CI 59.6 to 65.7 and 47.2, 95% CI 44.4 to 50.0, respectively, p=0.013). Human error and technical characteristics were assessed as more likely to be the causes of false positives (p<0.001); the level of the viral load as the cause of false negatives (p<0.001).

Conclusions

While some aspects of the swab for SARS-CoV-2 are well grasped, others are not and may have a strong bearing on the general public’s health and well-being. The obtained findings provide policymakers with a detailed picture that can guide the design and implementation of interventions for improving efficient communication with the general public as well as adherence to precautionary behaviour.