National Engineering Laboratory Research Articles

Environmental impact assessment of the manufacture and use of N- type and P-type photovoltaic modules in China

For a long time, solar power has been considered a clean and non-polluting energy source because it absorbs sunlight without consuming other energy or materials and does not emit pollutants. Nevertheless, the manufacturing and end-of-life stages of solar power systems leave an environmental footprint and produce pollutants. Hence, a global perspective on photovoltaic (PV) systems using life cycle assessment methodology is necessary. Here, we investigated the life cycle impacts of P- and N-type PV modules in terms of their energy consumption, carbon emissions, and human toxicity potential. In addition, the energy payback durations of P- and N-type PV modules were computed. In this study, we used the Life Cycle Assessment Basic Database from the National Engineering Laboratory of Industrial Big Data Application Technology at Beijing University of Technology to create a life cycle assessment model for N-type PV modules. Subsequently, we performed a life cycle assessment of Chinese silicon N-type- and P-type PV modules. The research system encompassed the production processes for metallic silicon materials, solar-grade silicon materials, silicon wafers, cells and modules, utilization, recycling, and other interrelated processes. We found that the production and processing of silicon-to-solar-grade polysilicon feedstock were crucial stages that significantly affected the energy consumption and environment of P- and N-type PV modules in China. The high electricity consumption of this process, combined with the dominance of coal power in China's electricity structure, contributed to the substantial energy consumption and environmental impacts of the PV modules. Therefore, this stage is critical for the low-carbon and environmentally sustainable manufacturing of N-type PV modules in China. Carbon emissions for both the P-type and N-type PV modules were lower only during the cell production phase but higher during the other stages when compared to the P-type and N-type PV modules. The n-type bifacial PV modules yielded the highest return on investment in terms of energy. Different regions and installation types have a substantial impact on the carbon emissions of P-type and N-type PV modules. Projections indicate that the potential to lower carbon emissions from n-type PV modules will increase by 2060.

Investigation of the transferability of calibration between alternative fluids for liquid and dense phase carbon dioxide flow measurement

Carbon Capture Utilisation and Storage (CCUS) technology is pivotal for achieving global emissions reduction goals. The rise in CCUS facilities, with a near doubling of global capture capacity, indicates industry momentum. Robust flow measurement across the CCUS transport and storage networks are essential for commercial contracts, financial incentives, and regulatory compliance since these are underpinned by accurate quantification of the CO2 quantity transferred across the CCUS chain. However, a critical gap exists in verification and quality assurance of flow meters as currently there are no traceable calibration facilities that operates with liquid and/or dense phase CO2. However, globally there are many accredited traceable water and oil calibration facilities in operation, which can meet the required flow rates and meter sizes. An experimental study was then conducted at TÜV SÜD National Engineering Laboratory, UK, and at the Institute for Energy Technologies, NO, to explore the transferability of calibration between water, oil, and CO2 using five flow meter technologies with the aim of providing a preliminary assessment of whether meters calibrated in alternative fluids can accurately measure liquid and supercritical CO2. The results suggest that this approach could work for Coriolis meters. The results also suggest caution in relying solely on using Equations of State to calculate density values and a recommendation is presented to currently employing direct density measurements until a more comprehensive understanding is achieved on Equations of State performance for CO2-rich mixtures. To the best of the author's knowledge this is the first time that such experimental investigation is conducted, and the results shared publicly.

A new correlation to determine the Lockhart-Martinelli parameter from vertical differential pressure for horizontal venturi tube over-reading correction

Venturi tubes are widely used to measure the gas flow rate in a wet-gas stream. To calculate the gas flow rate, wet-gas Venturi tubes require the liquid loading (i.e. Lockhart-Martinelli parameter) to be known as an input to a so-called over-reading correction correlation. It is challenging to derive the Lockhart-Martinelli parameter without installing additional devices in series to the Venturi tube thus adding significant cost and complexity. A relatively low cost and easy to implement method is to derive the Lockhart-Martinelli parameter by measuring the pressure drop across the Venturi tube or along a pipe section. A correlation that predicts the Lockhart-Martinelli parameter by measuring the pressure drop along a vertical pipe section downstream of the Venturi tube is presented. The correlation was obtained by fitting experimental results from TUV-SUD National Engineering Laboratory's wet-gas test facility with nitrogen-water in a 4″ vertical pipe, Lockhart-Martinelli from 0.04 to 0.29, and gas Froude number from 1 to 2.7. Further experiments were conducted at Spirax Sarco Engineering plc to evaluate the performance of the proposed correlation under steam-water conditions. Tests were conducted with steam-water in a vertical 2″ pipe, Lockhart-Martinelli from 0.005 to 0.064, and gas Froude number from 0.55 to 1.35. The Lockhart-Martinelli parameter is predicted within ±0.035 absolute value with the proposed new correlation for both the National Engineering Laboratory and Spirax Sarco datasets. Gas flow rate values within approximately ±5% error are obtained with the proposed correlation together with ISO/TR 11583 over-reading correlation for the NEL dataset. Although further improvements to the proposed method are required, this work demonstrates the efficacy of an agile, simple, and low-cost differential pressure method to aid the Venturi meter to determine the gas mass flow rate in wet-gas flow.

Computation of Total Electric Field Considering Natural Wind Under High-Altitude UHVDC Transmission Lines

With the rapid development of ultra high-voltage DC (UHVDC) transmission technology, the total electric field problem in high-altitude dc transmission lines is more important. Therefore, this article proposes a calculation model of the ion flow field at high altitude based on the natural wind model and the gas motion theory. First, the initial charge density is assumed, and then, Poisson’s equation is solved by the finite-element method (FEM). The measured wind speed and altitude are introduced into the natural wind model and the ion mobility model, and the natural wind speed and the ion mobility of each node are obtained. Subsequently, the current continuity equation is calculated by this information and the upstream FEM. When the calculation results do not meet the steady-state convergence conditions, the charge density on the conductor surface is iteratively corrected. The calculation model is verified by the measurement results of the ±800-kV UHVDC transmission line at the National Engineering Laboratory for Ultrahigh Voltage Technology (Kunming) of the China Southern Power Grid. The research shows that with the increase of altitude, the ion mobility gradually becomes larger, and the total electric field at ground level also increases. Due to the influence of wind, the peak value of the total electric field at ground level is obviously shifted, and the maximum peak values are on the downwind side. This model in this article can accurately calculate the total electric field of UHVDC transmission lines at high altitude considering the natural wind and provide a reference for the design of transmission lines.

A study on pick cutting properties with full-scale rotary cutting experiments and numerical simulations.

To investigate the cutting forces on road-header picks, a series of full-scale single-pick rotary cutting tests on sandstone samples were conducted at the National Engineering Laboratory of Coal Mining Machinery and Equipment, China. The primary objective of this study is to optimize the cut spacing and to verify the numerical simulation results. Cutting forces are investigated under different cutting depths and cut spacings. Cut spacing is optimized by analyzing the specific energy, coarseness index, and cutting force. The rock cutting process is simulated on a pick model using the PFC3D software. Rock samples are used as models, and particle assemblies and micro-properties are calibrated by uniaxial compressive strength tests and Brazilian disc tensile strength tests. The optimum ratio of cut spacing to cutting depth for the analyzed sandstone is determined to be in the range of 3 to 4. The experimental results show that a higher coarseness index corresponds to an increased block ratio, and specific energy decreases under optimum cutting conditions. Forces acting on the pick model are determined by simulation. A reasonable agreement exists between the experimental and numerical simulation results regarding the pick forces. The influence of the cut spacing on the rock-breaking effect observed in the experiments is confirmed by numerical simulations. Therefore, numerical simulations using the PFC3D software represent a reliable method for predicting the pick forces.

An Invention Promising Less Carbon and Cost Could Allow More Stranded-Gas Development

A promising innovation with a ponderous name, pseudo dry gas (PDG), opens the possibility of developing stranded-gas fields in remote locations by making it possible to build far-longer tiebacks and ultimately produce more gas. But it comes with a major challenge: convincing offshore producers that they can rely on a subsea system that separates natural gas from the condensate and water in the production stream. The benefits are obvious. Being able to move gas and liquids separately is a lot more efficient and avoids problems associated with multiphase flow, particularly slug formation, which requires topsides equipped to catch the slugs. Separation also reduces backpressure, which is expected to increase the ultimate recovery from those fields. In the 4 years since the idea debuted at the Offshore Technology Conference (OTC), a small team in Worley’s Aberdeen office has built and successfully tested a small-scale prototype of a flow loop with the support of an industry partnership including three unnamed energy companies. Even with all of that, they needed to establish an added benefit to win a critical government grant to build and test a full-scale prototype for high-pressure testing. This energy-efficient alternative promises to significantly reduce carbon emissions compared to offshore compression and platforms. “As the energy industry strives toward sustainability, it’s important to support solutions that enable decarbonization,” said Andy McDonald, head of Low Carbon Transition at Scottish Enterprise, which put up £765,000 ($1 million) to support testing, according to a release from Worley. They are currently building a full-scale unit to be tested later this year at the National Engineering Laboratory in Glasgow, pushing the device closer to the technical readiness level that will allow an offshore field test. This new approach is competing against two well-established alternatives—platform-based development and compression. Their counterargument is based on the energy efficiency of separation, which limits the compression required and the steel that goes into platforms. When comparing the energy required, Thomas Lee, lead development engineer at Worley who co-invented PDG, pointed out that the power required for separation is measured in thousands of watts, while compression requires millions of watts. “It effectively decarbonizes upstream gas production. It gets rid of compression from the gas field. The amount of CO2 from this operation is really low,” Lee said. The amount of carbon and cost also depends on the location of the compression equipment. Normally it has been on a platform, which provides power and easy access for maintenance but adds costs and carbon. Worley’s inline separator is built to fit into the space filled by a standard joint of pipe (Fig. 1). Onshore compression is also an option, and Equinor and Shell have shown that compression can be done subsea. Compression has been used in projects around the world, the majority of which are in fields that hold reserves of 10 Tcf or more (Fig. 2).

Determination of void fraction in wet-gas vertical flows via differential pressure measurement

The measurement of void fraction in multiphase flow is important for a wide range of industrial processes. Existing methods for void fraction measurement require intrusive, expensive and potentially hazardous equipments which constrict the flow, adding both capital and operational costs. Two phase flow experiments were carried out at the National Engineering Laboratory (NEL) to measure void fraction via pressure drop in a vertical pipe. Additional experiments are carried out at Spirax Sarco Inc. to validate the efficacy of the method on steam/water flow mixtures at high temperature and pressure, in gas mass fraction range between 0.17 and 0.95 and void fraction range between 0.75 and 1.0. The void fraction calculated by the presented differential pressure (dP) method is confirmed via established correlations. The work demonstrates the efficacy of a low cost, non-intrusive method to determine void fraction in two phase flow over a wide range of flow conditions.

The consistency of pressure effects between three identical Coriolis flow meters

Coriolis flow meters are one of the most popular flow measurement technologies in the world today for high accuracy measurement of single-phase liquids, gases and even slurries. They are capable of measuring both mass and density directly and can also infer the volume flow. They can be installed in challenging process environments and have been successfully deployed with non-Newtonian fluids, high viscosity fluids, pulsating flows and even at extreme temperatures and pressures.However, it is known that operating most Coriolis flow meters at a pressure which differs from the original calibration pressure requires compensation else significant measurement errors will occur. Pressure compensation coefficients appear to vary by manufacturer, meter geometry and sensor material. Furthermore, the manufacturer published pressure compensation coefficients are not fully traceable. To date, there has not been sufficient research exploring the consistency of the pressure compensation for identical Coriolis flow meters.This paper presents the findings of a research conducted at the TÜV SÜD National Engineering Laboratory (NEL) Elevated Pressure and Temperature (EPAT) oil flow facility to investigate the pressure effect uniformity for matching Coriolis devices. The first stage of the experimental programme calibrated three identical DN80 Coriolis flow meters at a range of pressures with no pressure compensation applied. A pressure compensation coefficient was then derived from the data and the Coriolis meters were then calibrated at two alternative pressures to ascertain the robustness of the coefficients and whether the compensation could be extrapolated successfully.From the experimental results, it can be concluded that the pressure effect for the three DN80 Coriolis flow meters was extremely repeatable and consistent with a discrepancy of less than 0.025% between the devices at 80 bar. Whilst the mass flow was significantly affected by fluid pressure, the fluid density did not appear to be influenced. The pressure corrected results were also well within the manufacturer specification of ±0.1%.

A novel risk score for in-hospital perioperative mortality of five major surgeries.

Risk-scoring tools for perioperative mortality adjustment are essential for inter-hospital quality comparisons, which are still lacking in China. Existing scores had significant disadvantages when applied in managerial practice. This study aimed to develop a simple risk score using highly accessible information that could appropriately adjust the perioperative mortality from major surgeries across tertiary Chinese public hospitals and provide a reference for other underdeveloped countries with the same need. A study cohort from 19 hospitals was randomly split into a development set and an internal validation set in the ratio of 7:3. Another cohort from six hospitals was used as an external validation set. All data were obtained from the military-hospital public services database of the National Engineering Laboratory of Application Technology in Medical Big Data. Patients aged above 18 years undergoing one of the five categories of major surgical procedures between 1 January 2010 and 31 December 2020 were identified. The multivariate logistic regression analysis was used to predict the risk of mortality and derive the risk score. The area under the receiver operating characteristic curve (AUC) and the Hosmer-Lemeshow goodness-of-fit test were used to assess the discrimination and calibration of the model, respectively. The study set included 45 558 cases, divided into a development set containing 31 891 cases and an internal validation set with 13 667 cases. Another cohort with 14 956 cases was used as an external validation set. The final included predictor variables were age, Elixhauser Comorbidity Index, condition at admission, admission route and the procedure. The predicted risk score ranged from -21.5 to 37.0 points. The model discriminated well in the development set, internal validation set, and external validation set. The AUC for them were 0.753 (Standard Error(SE) 0.016, 95% Confidence Interval(CI): 0.721,0.784), 0.790 (SE 0.025, 95% CI: 0.742,0.839), and 0.766(SE 0.019, 95% CI: 0.728, 0.804), respectively. P values in the Hosmer-Lemeshow goodness-of-fit test were all above 0.05, indicating a good calibration. This risk-scoring model was proved to have satisfactory performance, allowing the rapid and effective risk adjustment of perioperative mortality when comparing the surgical quality in tertiary hospitals in China and other underdeveloped regions.

Thermo-mechanical behavior of an ablated reactor pressure vessel wall in a Nordic BWR under in-vessel core melt retention

The reactor pressure vessel (RPV) of a nuclear reactor is one of the key safety barriers preventing radioactive environmental releases during a severe accident. One of the promising strategies of severe accident management (SAM) is to retain the molten core having continuous decay heat inside the RPV by natural water cooling of the external vessel surface. The feasibility of such a strategy relies on complex safety analyses including accurate prediction of vessel thermo-mechanical behavior which can be assessed by mechanical stresses and strains.In this paper, we present the stress–strain response of an ablated RPV of a Nordic boiling water reactor (BWR) to dynamic thermomechanical loads set by expanding volumetrically heated molten pool inside the RPV cooled by water at the external surface. MELCOR 2.2.9541 severe accident code is used to simulate the in-vessel behavior and provides the input conditions for dedicated structural analysis of the RPV using ANSYS® Mechanical APDL 19.2. A creep model of the SA533B1 vessel steel is validated against uniaxial creep tests carried out by INEL (Idaho National Engineering Laboratory) and creep tests performed at CEA (French Alternative Energies and Atomic Energy Commission) as part of the OLHF (OECD Lower Head Failure) Project. Two generic severe accident scenarios are considered: (i) Station Blackout (SBO) and (ii) Station Black-out and Loss-of-coolant Accident (SBO + LOCA). In both scenarios, we found that the RPV has maintained structural integrity considering two failure criteria: stress-based and strain-based.

Static Strain Analysis of CRTS I Bi-Block Ballastless Track

In this paper, relying on the National Engineering Laboratory of High-Speed Railway Construction Technology, a full-scale model of the double-block ballastless track structure is established, and the strain analysis of the layered track structure under different static loads is carried out, which has a certain practical significance for the design and maintenance of the high-speed railway ballastless track in our country. Research conclusion: (1) Under the action of static load, the sleeper directly under the rail is under compression; the four corners of the sleeper are tensile strain; (2) The strain at each measuring point on the surface of the track slab around the sleeper is compressive strain; the edge of the top surface of the track slab is compressive strain; The longitudinal strain at the bottom of the side of the track slab is tensile strain; (3) Under static load, the longitudinal strain measurement point on the top surface of the base plate is tensile strain at a distance of two sleepers from the static load position; the longitudinal strain at the bottom of the side of the base plate is tensile strain.

Deep Brain Stimulation Initiative: Toward Innovative Technology, New Disease Indications, and Approaches to Current and Future Clinical Challenges in Neuromodulation Therapy.

Deep brain stimulation (DBS) is one of the most important clinical therapies for neurological disorders. DBS also has great potential to become a great tool for clinical neuroscience research. Recently, the National Engineering Laboratory for Neuromodulation at Tsinghua University held an international Deep Brain Stimulation Initiative workshop to discuss the cutting-edge technological achievements and clinical applications of DBS. We specifically addressed new clinical approaches and challenges in DBS for movement disorders (Parkinson's disease and dystonia), clinical application toward neurorehabilitation for stroke, and the progress and challenges toward DBS for neuropsychiatric disorders. This review highlighted key developments in (1) neuroimaging, with advancements in 3-Tesla magnetic resonance imaging DBS compatibility for exploration of brain network mechanisms; (2) novel DBS recording capabilities for uncovering disease pathophysiology; and (3) overcoming global healthcare burdens with online-based DBS programming technology for connecting patient communities. The successful event marks a milestone for global collaborative opportunities in clinical development of neuromodulation to treat major neurological disorders.

Characteristics of prescriptions and costs for acute upper respiratory tract infections in Chinese outpatient pediatric patients: a nationwide cross-sectional study

BackgroundTo understand the characteristics of prescriptions and costs in pediatric patients with acute upper respiratory infections (AURI) is important for the regulation of outpatient care and reimbursement policy. This study aims to provide evidence on these issues that was in short supply.MethodsWe conducted a retrospective cross-sectional study based on data from National Engineering Laboratory of Application Technology in Medical Big Data. All outpatient pediatric patients aged 0–14 years with an uncomplicated AURI from 1 January 2015 to 31 December 2017 in 138 hospitals across the country were included. We reported characteristics of patients, the average number of medications prescribed per encounter, the categories of medication used and their percentages, the cost per visit and prescription costs of drugs. For these measurements, discrepancies among diverse groups of age, regions, insurance types, and AURI categories were compared. Kruskal-Wallis nonparametric test and Student-Newman-Keuls test were performed to identify differences among subgroups. A multinomial logistic regression was conducted to examine the independent effects of those factors on the prescribing behavior.ResultsA total of 1,002,687 clinical records with 2,682,118 prescriptions were collected and analyzed. The average number of drugs prescribed per encounter was 2.8. The most frequently prescribed medication was Chinese traditional patent medicines (CTPM) (36.5% of overall prescriptions) followed by antibiotics (18.1%). It showed a preference of CPTM over conventional medicines. The median cost per visit was 17.91 USD. The median drug cost per visit was 13.84 USD. The expenditures of antibiotics and CTPM per visit (6.05 USD and 5.87 USD) were among the three highest categories of drugs. The percentage of out-of-pocket patients reached 65.9%. Disparities were showed among subgroups of different ages, regions, and insurance types.ConclusionsThe high volume of CPTM usage is the typical feature in outpatient care of AURI pediatric patients in China. The rational and cost-effective use of CPTM and antibiotics still faces challenges. The reimbursement for child AURI cases needs to be enhanced.

Fenômeno de meandro do vento e a função de autocorrelação calculada com base na concentração de poluentes simulada pelo modelo transiente 3D-GILTT

The aim of this work is to present a pollutants dispersion transient model in low wind conditions to simulate the behavior of the pollutants plume in the atmosphere, considering in the model the u e v horizontal wind components simulated by the LES-PALM model. The dispersion model is based in the advection-diffusion equation and represent by this methodology the wind meandering phenomenon. The Generalized Integral Laplace Transform Technique in three dimensions (3D- GILTT) solves the transient advection-diffusion equation. The data utilized to initialize the simulations are data of the low wind INEL (Idaho National Engineering Laboratory) experiment accomplished in EUA. The results show that the dispersion model reproduces the wind meandering phenomenon, in other words, the autocorrelation function of the concentration simulated over an hour presents the negative lobule, similarly to observed lobules in the u and v wind components. Therefore, the model simulates the pollutants plume in a satisfactory way and can be used to air quality regulatory applications in low wind and wind meandering conditions.

Simulation of three-dimensional transient pollutant dispersion in low wind conditions using the 3D-GILTT technique

The aim of this work is to present a transient model in low wind conditionsto simulate the pollutants dispersion in the atmosphere. The dispersion model is based in the advection-diffusion equation and it considers the zonal and meridional components of the wind. The transient advection-diffusion equation is solved using integral transform techniques. In this work, the generalized integral transform and Laplace techniques are used, known in the literature as GILTT and which applied to the three-dimensional problem is called 3D-GILTT (Three-dimensional Generalized Integral Laplace Transform Technique). To validate the model, data from INEL experiment (Idaho National Engineering Laboratory) carried out in the USA were used. The model simulates the observed concentrations in a satisfactory way and can be used for regulatory air quality applications

Vertically installed Venturi tubes for wet-gas flow measurement: Possible improvements to ISO/TR 11583 to extend its range of applicability

Venturi tubes are commonly used for wet-gas flow measurement, and the majority of commercial wet-gas flow meters generally include a Venturi tube installed vertically with embedded secondary instrumentation. The presence of the liquid causes an increase in the measured differential pressure and results in the Venturi tube over-reading the actual amount of gas passing through the meter. Most of the research in the literature is focused on the investigation of the over-reading for horizontally oriented Venturi tubes, thus limiting the development of over-reading correlations for vertical installation. An experimental campaign was recently conducted at the TÜV SÜD National Engineering Laboratory (NEL) high-pressure wet-gas loop, where three Venturi tubes of the same nominal diameter (4”) but different throat to inlet diameter ratio (0.4, 0.6, 0.75) were tested, installed vertically after a blind tee. The results of this experimental campaign are presented in this paper and the effects of various parameters (line pressure, gas Froude number, diameter ratio) on the over-reading are briefly discussed. It is shown that the over-reading correlation included in the ISO/TR 11583:2012 and developed for horizontally oriented Venturis, is not applicable to vertically oriented Venturis. However, if modified, the correlation included in the ISO/TR 11583 is capable of meeting its stated uncertainty limits for the experimental data presented here for vertically installed Venturis.

ICAESEE 2019 Preface

The 2019 5th International Conference on Advances in Energy Resources and Environment Engineering (ICAESEE 2019) took place on December 6-8, 2019 in Chongqing, China. The conference is organized by Yantai University, China, China Coal Technology Engineering Group, China Coal Research Institute, and National Engineering Laboratory for Deep Shaft Construction Technology. Continuing the success of previous four editions, the fifth ICAESEE managed to attract a great number of researchers, developers, engineers, academicians as well as industrial professionals from all over the world to present their research results in the field of energy resources and environment engineering.ICAESEE 2019 provided all the participants with an opportunity to present their research results to the following areas of interest• Energy Chemical Engineering and Energy Saving Technology• Environmental Analysis and Pollution Control Engineering• Power System Management and Automation• Resource Exploration and Equipment Processing EngineeringProfessors from different areas were invited to deliver high-level keynote speeches regarding the latest information in their respective expertise areas. The conference provided a platform for those that are of interest to the topics to interact with the experts to get their advice and consult as well as collaboration opportunities.The success and prosperity of the conference was also reflected by the high level of the papers received. Through the strict peer review process, 399 papers were accepted to be published in IOP Conference Series: Earth and Environmental Science (EES) (Online ISSN: 1755-1315 Print ISSN: 1755-1307) and will be submitted to EI Compendex, Scopus, CPCI for indexing.On behalf of the Committees of ICAESEE 2019, we would like to express our gratitude to all the participants, presenters, contributors and reviewers as they gave us full support. We sincerely hope that ICAESEE conference will serve as an ideal forum for academia, industrial practitioners and government agents.List of Organizing Committees, Logos are available in this pdf.

Study on the Selection of New Parallel Gap of 500kV Transmission Line at High Altitude

The current relevant power industry standards regulate the structure and size parameters of transmission line parallel gap. But practical operation experience proves that protection failure often occurs with the 500kV parallel gap recommended in the standards. A new 500kV parallel gap suitable for general areas had been developed for the purpose of improving the efficiency of protection, reducing the damage to insulator string caused by lightning flashover, and reducing the line lightning strike outage rate. However, under the condition of high altitude, the dimension parameters of general areas cannot be directly used in the new 500kV parallel gap. This paper conducts some tests on parallel gap of different size parameters with different serial lengths at UHV engineering technology (Kunming) national engineering laboratory at an altitude of 2100 m, including, U50% lightning impulse test, volt-second characteristic test, visible corona and radio interference test. Protection effectiveness have been analyzed. The results prove that the recommended transverse extension lengths of parallel gap electrodes are 750/750mm and 800/800mm respectively, when the number of insulators is 33 and 37.

Variable- versus constant-frequency deep-brain stimulation in patients with advanced Parkinson\u2019s disease: study protocol for a randomized controlled trial

BackgroundDeep-brain stimulation targeting the subthalamic nucleus (STN) can be used to treat motor symptoms and dyskinesia in the advanced stages of Parkinson’s disease (PD). High-frequency stimulation (HFS) of the STN can lead to consistent, long-term improvement of PD symptoms. However, the effects of HFS on the axial symptoms of PD, specifically freezing of gait, can be limited or cause further impairment. While this can be alleviated via relatively low-frequency stimulation (LFS) in selected patients, LFS does not control all motor symptoms of PD. Recently, the National Engineering Laboratory for Neuromodulation reported preliminary findings regarding an efficient way to combine the advantages of HFS and LFS to form variable-frequency stimulation (VFS). However, this novel therapeutic strategy has not been formally tested in a randomized trial.Methods/designWe propose a multicenter, double-blind clinical trial involving 11 study hospitals and an established deep-brain stimulation team. The participants will be divided into a VFS and a constant-frequency stimulation group. The primary outcome will be changes in stand–walk–sit task scores after 3 months of treatment in the “medication off” condition. Secondary outcome measures include specific item scores on the Freezing of Gait Questionnaire and quality of life. The aim of this trial is to investigate the efficacy and safety of VFS compared with constant-frequency stimulation.DiscussionThis is the first randomized controlled trial to comprehensively evaluate the effectiveness and safety of VFS of the STN in patients with advanced PD. VFS may represent a new option for clinical treatment of PD in the future.Trial registrationClinicalTrials.gov, NCT03053726. Registered on February 15, 2017.

4th International Conference on Advances in Energy Resources and Environment Engineering

ICAESEE 2018 PrefaceThe 2018 4th International Conference on Advances in Energy Resources and Environment Engineering (ICAESEE 2018) took place on December 7-9, 2018 in Chengdu, China. The conference is organized by The College of Environment and Planning, Henan University, China Coal Research Institute CCRI and National Engineering Laboratory of Coal Mine Deep Well Construction Technology. Continuing the success of previous three editions, the fourth ICAESEE managed to attract a great number of researchers, developers, engineers, academicians as well as industrial professionals from all over the world to present their research results in the field of energy resources and environment engineering.ICAESEE 2018 provided all the participants with an opportunity to present their research results to the following areas of interest:• Energy Engineering and Energy Technology• Environmental Science and Environmental Engineering• Electricity Supply Systems• Exploration and Utilization of Resources and Sustainable Development• Energy Economy and ManagementProfessors from different areas were invited to deliver high-level keynote speeches regarding the latest information in their respective expertise areas. The conference provided a platform for those that are of interest to the topics to interact with the experts to get their advice and consult as well as collaboration opportunities.The success and prosperity of the conference was also reflected by the high level of the papers received. Through the strict peer review process, more than 350 papers were accepted to be published in IOP Conference Series: Earth and Environmental Science (EES) (Online ISSN: 1755-1315 Print ISSN: 1755-1307) and will be submitted to EI Compendex, Scopus, CPCI for indexing.List of Organizing Committees are available in this PDF.