Prequalification Test Research Articles

Seismic pre-qualification tests of EC8-compliant external extended stiffened end-plate beam-to-column joints

An experimental and numerical campaign was carried out to validate the design procedure and prequalify extended stiffened end-plate (ESEP) joints for ductile seismic resistant moment-resisting frames in the framework of Eurocodes. In fact, the tested ESEP joints have been designed with the aim of guaranteeing ductile and dissipative seismic response in accordance with the principles of the hierarchy of resistances to enforce plastic deformations in ductile components of the joints. Two alternative types of dissipation mechanisms are promoted, namely either (i) plastic deformations solely in the connected beam using full strength joints or (ii) plastic deformations in both the beam and the connection using equal strength joints. The adopted design criteria and technological details are described and discussed. The results of experimental tests confirmed the expected yielding mechanisms of the joints, which satisfied the acceptance criteria for both North American and European prequalification. Finite element simulations of ESEP joints have been validated against the experimental results and have been used to investigate the local response of the joints, thus highlighting the influence of both geometrical and mechanical parameters.

Pre Qualification Test on 220 KV Cable System – CPRI Experience

With the development of XLPE cables and associated accessories up to 500 kV voltage level, XLPE Cable Systems are becoming the main back bone of the Power Distribution and Transmission system. The basic requirement of power cable is that it shall withstand the electrical, thermal, mechanical and environmental stresses imposed on it during its expected life of 25 to 35 years. Generally the development of cable for EHV applications is achieved through increased stress design, which demands very stringent quality requirements during production of cables and development of accessories. Since different designs are available for cables and accessories, it is essential to carry out long duration test to establish their compatibility and reliability. IEC 62067 for extra High voltage Cable accessories have incorporated the pre-qualification tests to check the long term reliability of the cable system in service before installation. This paper highlights the details of Pre qualification test on 220 KV Cable system conducted at CPRI for the first time in India.

Correlations between standard accelerated tests for protective organic coatings and field performance

Accelerated testing is widely used in development and pre-qualification of protective organic coatings. In this work 26 coating systems have been investigated in a 2-year C5 atmospheric exposure field test, ISO 9227 salt spray test, ISO 12944-9 cyclic ageing and ISO 16773 electrochemical impedance spectroscopy measurement of coating resistance. Of the 26 coating systems, 16 have epoxy mastic primers and 10 have zinc rich epoxy primers. In the field test, the zinc rich primer improved corrosion creep resistance from scribe by a factor of about 10. However, this is not reflected in any of the accelerated lab tests. The lab tests all show rather poor correlation to the field test with respect to corrosion creep. All the coatings had little corrosion creep from scribe in the field test, even the coating systems with epoxy mastic primers. The large focus on this parameter in coating pre-qualification testing, e.g. in ISO 12944-6 and 12944-9, may therefore not be justified.

Polymer electrolyte membrane electrolyzer and fuel cell system characterization for power system frequency control

This work focuses on tests for control reserve of a novel Power-to-Gas-to-Power platform based on proton exchange membrane technologies and on pure oxygen instead of air in the re-electrification process. The technologies are intended as a further option to stabilize the power system, therefore, helping integrating renewable energy into the power system. The tests are based on the pre-qualification tests used by Swissgrid, but are not identical in order to capture the maximum dynamics by the plants. The main characteristics identified are the ramping capabilities of ±8% per unit per second for the electrolyzer system and ±33% per unit per second for the fuel cell system. The ramping capabilities are mainly limited by the underlying processes of polymer electrolyte membrane technologies. Additionally, the current and projected round-trip efficiencies for Power-to-Gas-to-Power of 39% in 2025 and 48% in 2040 are derived. Furthermore, during the successful tests, the usage of oxygen in the present Power-to-Gas and Gas-to-Power processes and its influence on the dynamics and the round-trip efficiency was assessed. In consequence, fundamental data on the efficiency and the dynamics of the Power-to-Gas-to-Power technologies is presented. This data can serve as basis for prospective assessments on the suitability of the technologies investigated for frequency control in power systems.

Predicting Cost Performance of Construction Projects from Projects Procurement Procedure

Abstract The purpose of this paper is to show by multivariate regression model if a defective procurement procedure leading to a contract award affects the smooth execution of a project in terms of its cost performance on the strength of the significance of the model. This investigation was conducted with a quantitative method of research by administering questionnaires to key industry players (clients, consultants, and contractors) engaged in construction projects (both civil and building works) in assessing contract award procedures, conditions for contract award after tender evaluation and criteria for contractors’ prequalification. Data from their field survey was analysed with mean item score to show hierarchal importance of factors and critical evaluation using multivariate analysis of variance. Findings showed that a poor and inappropriate contract award procedure has divergence from efficient project cost management based on the corollary of mean score values of contract award procedures, conditions for the award and prequalification test. The practical implication of this, is that an unbiased contract award procedure will apparently lead to a lesser strenuous project management effort towards mitigating cost spills and overruns for a lesser project abandonment if the right contractor with the right capabilities is awarded the contract. These implications stem from the originality of the investigation arising from F-value statistics (7.406), t-value statistics (3.046), and p-value of 0.003.

Evidence collected for peer review of buckling-restrained braced frames in New Zealand

Buckling-restrained braces (BRBs) form a bracing system that provides lateral strength and stiffness to a building. These systems have been shown to provide larger energy dissipation in severe earthquake events compared to concentrically and eccentrically braced frames (CBFs and EBFs). However, unlike CBFs and EBFs there is no guidance document or specific instructions in regulatory standards for the design of buckling-restrained braced frames (BRBFs) in New Zealand. This makes it difficult for structural engineers to be aware of all the strength and stability considerations required for the safe design of BRBFs. Currently, structural designs that include BRBFs require a peer-review to gain building compliance. The American standard ANSI/AISC 341-16 is the adopted document used in New Zealand for guidance in how to collect evidence showing a BRBF system will perform as intended. However, as ANSI/AISC 341-16 is not a governing document in New Zealand, instructions within the document are not enforced and can be made to fit within the constraints of a building project. By way of example, this paper presents the experimental test process and results acquired from pre-qualification testing of three different commercially available BRB architypes. Of the three BRB designs investigated, one failed prematurely due to global buckling. A manufacturing error was the likely cause of this premature failure. This failure highlights the need for strict quality control during fabrication. All remaining BRBs performed well, meeting the acceptance criteria set out in ANSI/AISC 341-16. Positive pre-qualification results meant the BRBs were installed in medium to high-rise buildings throughout New Zealand. The importance of sub-assemblage testing to assess the performance of a BRB and its frame components is also discussed. Finally, the capability of high fidelity modelling to supplemental physical testing is also presented.

The effect of temperature and stress coefficients of electrical conductivity on the life of HVDC extruded cable insulation subjected to type test conditions

This paper investigates the effect of temperature and stress coefficients of electrical conductivity of the insulation material on the life and reliability of HVDC extruded cables subjected to type test load cycles according to CIGRE Technical Brochure 496. The investigation is done by refining a procedure for the estimation of cable insulation life and reliability in the presence of load cycles, developed and implemented in a previous stage of this research, but applied so far to prequalification test load cycles only. Electric field is calculated using both the rigorous approach based on Maxwell's equations for transient electric field computation (exact method) and the closed-form steady-state Eoll's formula often employed in the preliminary design of DC cable insulation (approximated method). This enables also to assess the accuracy of the overall approximation involved by Eoll's formula in the case of type test conditions.

Review of CIGRE TB 496 regarding Prequalification Test on Extruded MVDC Cables

The well established HVDC power transmission technology is currently also seen as a viable solution for the medium-voltage range and there is a growing demand for extruded MVDC cables. The CIGRE TB 496 gives recommendations for highvoltage tests on extruded DC cable systems with rated voltage up to 500 kV, but do not consider the technical differences between HVDC and MVDC cables. Therefore, the prequalification test described in CIGRE TB 496 is analysed and an optimised PQ test is proposed for extruded MVDC cables.

Influence on Aggregation Structure Changes of Retired Cross-linked Polyethylene (XLPE) Cable Insulation under Pre-qualification Test

In order to investigate the cross-linked polyethylene (XLPE) insulation characteristics of a retired high-voltage cable that has been in operation for 16 years and to evaluate the reliability of reusing it for practical operation, a 180-day pre-qualification test method was applied to a section of this cable to inspect the changes of aggregation structure. In this paper, the electric field and the thermal field of the inner, medium and outer positions of the insulation under the accelerated aging test were analyzed and converted to the corresponding equivalent condition at the surface of the conductor core. It can be found that equivalent testing conditions of the medium and outer positions are close to the cable practical operation condition. The diagnostic measurements of fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (X-ray) were conducted to analyse the aggregation structure of the samples. The results showed that the molecular chain of the inner position of the cable insulation was damaged and the crystalline structure was slightly degraded under high-strength test condition. On the contrary, the crystalline structure of medium and outer positions were both improved after the accelerated aging test because of the reduction of the impurities and the annealing effect. So it can be expected that the rest of this retired cables still have the potential to reuse in long-term actual operation condition.

Evaluating containment effectiveness of A2 and B2 biological safety cabinets.

This study investigates the use of a canopy-connected recirculating class II type A2 biological safety cabinet (BSC) as an alternative to the B2 when preparing volatile, sterile compounded preparations. Selection of the appropriate BSC for processes that use subgram levels of volatile chemicals is difficult due to a lack of quantitative containment evidence by cabinet type. There is a perception that hazardous compounding must be done in a B2 cabinet due to the potential for vapors, and this study seeks to challenge that perception. In total, 5 tests, 3 prequalification tests and 2 containment capability tests, were conducted on a single cabinet of each type at sterile compounding pharmacies. Prequalification tests were performed to verify that each BSC was operating properly. Each cabinet was certified to NSF-ANSI 49-2016, particle counted per ISO 14644-1:1999, and subjected to a qualitative video smoke study. Once these tests confirmed the expected working conditions, 2 containment capability tests were conducted. The containment testing included tracer gas testing per ASHRAE 110:2016 section 8.1.1 through 8.1.13, and cyclophosphamide sampling during sterile compounding of the drug material. Both cabinets passed all the prequalification tests. During the ASHRAE tracer gas testing the A2 cabinet was able to contain a tracer gas 92% to 160% as effectively as the B2 cabinet depending on the position of the gas ejection. During sterile compounding the airborne cyclophosphamide sampling captured samples of less than 1.0 ng at all locations for both the A2 and B2 cabinets. The data generated from this study demonstrate that use of an A2 for hazardous compounding can provide a comparable level of safety for the environment, users, and product while having less stringent airflow requirements relative to a B2. The simpler requirements for an A2 make them an appealing alternative as they have the potential to reduce the overall operating costs associated with a compounding pharmacy while maintaining safe levels of containment.

PENGARUH KUALITAS PELAYANAN TERHADAP KEPUTUSAN PEMBELIAN KONSUMEN DI ALFAMART KOTA PALANGKA RAYA

Service quality gives encouragement to consumer to tie a good association with a company. Good service will give an impact to decision of consumer to buy and also to the company itself. A good service quality is very important to create a consumer’s satisfaction, especially in direct proof, capability, attentiveness, and warrant of a consumer’s satisfaction. According to that reasons, so the statement of the problem of this research is the influence of service quality to consumer’s buying decision in Alfamart in Palangka Raya city. This research is using a quantitative approach with survey. A population of this research is consumer of Alfamart in Palangka Raya city. The sample that is taken for this research amounts to 96 respondents which is taken with random sampling. Furthermore, for prequalification test is using normality test with Kolmogorov smirnov and Q-Q plot. Data analysis method is using correlation of product moment and simple regression using SPSS 16. From this study, it is found that the quality of the service and consumer’s buying decision in Alfamart in Palangka Raya city have strong relation according to the result of coefficient of product moment which amounts to 0,810. It is also found the amount of sig that is 0,000 which means there are significant relation. Furthermore, test of simple regression shows the amount of determination of coefficient 0,656 which means the influence of service quality to the consumer’s buying decision is 65,6 %. It is found also the amount of t count which is 13,386 which is bigger than t table, so it can be concluded that service quality has significant influence to consumer’s buying decision.

Insulation performance evaluation of HV AC/DC XLPE cables by 0.1 Hz tan δ test on circumferentially peeled samples

The XLPE insulations of three 110 kV AC cables with different manufacturers and operation histories and two 160 kV DC cables before and after the one-year prequalification test are studied in this paper. Slice samples are taken from different radial locations of the cable insulation layers by a circumferential peeling method and measurements of discharge current, dielectric spectrum and VLF loss angle tangent are carried out on the inner, middle and outer insulation parts respectively. It is found that for AC cables under test, the older the cable is, the more slowly the discharge current decays, and the greater the performances of three parts differ. As for the dielectric spectrums, tan δ decreases when the frequency increases from 0.05 to 1,000 Hz, and a longer service life causes a larger amplitude of variation. Besides, the three insulation parts give similar values of tan δ at 50 Hz, while those at 0.1 Hz differ from each other, especially for cables long-term service-aged. A characteristic parameter defined as the ratio of tan δ under 0.1 Hz to 50 Hz is proposed for the purpose of insulation condition evaluation, and its value becomes larger as the result of site operation for AC cables and long-term test for DC cables. VLF tan δ are measured under four levels of the 0.1 Hz voltage, and a normalization processing is performed by using outer part as the reference for AC cables and middle part for DC ones. The deterioration degree of material property can be reflected by not only the voltage stability of tan δ value, but also the performance difference among different parts of a cable insulation body. The electrical and thermal stresses, either from the site operation or from laboratory tests, can result in a decreased voltage stability and an increased performance difference. Since above conclusions are applicable to the XLPE insulation under AC operation and DC test, the preliminary work of this paper can be considered as a good start for the exploration of using VLF tan δ to assess the insulation condition of HV AC and DC cables.

Modelling and measurement of high‐frequency conducted electromagnetic interference in DC–DC converters

Conducted electromagnetic compatibility (EMC) noise qualification tests are normally carried out after a prototype has been designed, built and tested and the process is repeated in the event of non-compliance. The ability to determine compliance with electromagnetic interference (EMI) standards at the design stage is therefore desirable. This study will present conducted EMC noise modelling and measurement techniques, yielding simulated and measurement noise results accurate enough to serve as a prequalification test at the design and prototyping stages, respectively. Accurate models of the power feed line connecting the line impedance stabilisation network to the device under test (converter), including the load are developed. Predictive conducted EMC modelling is accomplished using detailed active level 3 SPICE-based models, creating a real-time circuit model consisting of a complete converter in its operational state, without the need to separate into equivalent models. Effects of the power feed-line length on EMI noise measurements are investigated as currently available literature has not dealt adequately with this issue. The modelling and measurements are performed using software and instruments available in a development laboratory..

The performance of community health workers in the management of multiple childhood infectious diseases in Lira, northern Uganda – a mixed methods cross-sectional study

BackgroundCommunity health workers (CHWs) have the potential to reduce child mortality by improving access to care, especially in remote areas. Uganda has one of the highest child mortality rates globally. Moreover, rural areas bear the highest proportion of this burden. The optimal performance of CHWs is critical. In this study, we assess the performance of CHWs in managing malaria, pneumonia, and diarrhea in the rural district of Lira, in northern Uganda.DesignsA cross-sectional mixed methods study was undertaken to investigate the performance of 393 eligible CHWs in the Lira district of Uganda. Case scenarios were conducted with a medical officer observing CHWs in their management of children suspected of having malaria, pneumonia, or diarrhea. Performance data were collected using a pretested questionnaire with a checklist used by the medical officer to score the CHWs. The primary outcome, CHW performance, is defined as the ability to diagnose and treat malaria, diarrhea, and pneumonia appropriately. Participants were described using a three group performance score (good vs. moderate vs. poor). A binary measure of performance (good vs. poor) was used in multivariable logistic regression to show an association between good performance and a range of independent variables. The qualitative component comprised seven key informant interviews with experts who had informed knowledge with regard to the functionality of CHWs in Lira district.ResultsOverall, 347 CHWs (88.3%) had poor scores in managing malaria, diarrhea, and pneumonia, 26 (6.6%) had moderate scores, and 20 (5.1%) had good scores. The factors that were positively associated with performance were secondary-level education (adjusted odds ratio [AOR] 2.72; 95% confidence interval [CI] 1.50–4.92) and meeting with supervisors in the previous month (AOR 2.52; 95% CI 1.12–5.70). Those factors negatively associated with CHW performance included: serving 100–200 households (AOR 0.24; 95% CI 0.12–0.50), serving more than 200 households (AOR 0.22; 95% CI 0.10–0.48), and an initial training duration lasting 2–3 days (AOR 0.13; 95% CI 0.04–0.41). The qualitative findings reinforced the quantitative results by indicating that refresher training, workload, and in-kind incentives were important determinants of performance.ConclusionsThe performance of CHWs in Lira was inadequate. There is a need to consider pre-qualification testing before CHWs are appointed. Providing ongoing support and supervision, and ensuring that CHWs have at least secondary education can be helpful in improving their performance. Health system managers also need to ensure that the CHWs’ workload is moderated as work overload will reduce performance. Finally, although short training programs are beneficial to some degree, they are not sufficient and should be followed up with regular refresher training.

Production of gaseous radiotracers for industrial applications

This paper describes prerequisite tests, analysis and the procedure for irradiation of gaseous targets and production of gaseous radioisotopes i.e. argon-41 (41Ar) and krypton-79 (79Kr) in a 100MWTh DHRUVA reactor located at Bhabha Atomic Research Center (BARC), Trombay, Mumbai, India. The produced radioisotopes will be used as radiotracers for tracing gas phase in industrial process systems. Various details and prequalification tests required for irradiation of gaseous targets are discussed. The procedure for regular production of 41Ar and 79Kr, and assay of their activity were standardized. Theoretically estimated and experimentally produced amounts of activities of the two radioisotopes, irradiated at identical conditions, were compared and found to be in good agreement. Based on the various tests, radiological safety analysis and standardization of the irradiation procedure, necessary approval was obtained from the competent reactor operating and safety authorities for regular production of gaseous radiotracers in DHRUVA reactor.

Manufacturing pre-qualification of a Short Breeder Unit mockup (SHOBU) as part of the roadmap toward the out-of-pile validation of a full scale Helium Cooled Pebble Bed Breeder Unit

The key components of the Helium Cooled Pebble Bed Test Blanket Module (HCPB TBM) in ITER are the Breeder Units (BU). These are the responsible for the tritium breeding and part of the heat extraction in the HCPB TBM. After a detailed design and engineering phase performed during the last years in the Karlsruhe Institute of Technology (KIT), a reference model for the manufacturing of a HCPB BU mock-up has been obtained. The mid-term is the out-of-pile qualification of the thermal and thermo-mechanical performance of a full-scale HCPB BU mock-up in a dedicated helium loop. Several key manufacturing technologies have been developed for the fabrication of the HCPB BU. In order to pre-qualify these techniques, a Short Breeder Unit mock-up (SHOBU) is under construction and to be tested. This paper aims at describing the relevance of SHOBU with a full-scale HCPB BU, the constitutive parts of SHOBU, the manufacturing and joining technologies involved, the assembly sequence (taking into consideration functional steps like its filling with Li4SiO4 pebbles or its assembly in the HCPB TBM) and the welding procedures studied. The paper concludes with a description of the required pre-qualification tests performed to SHOBU, i.e. pressure and leak tightness tests, according to the standards.

Fabrication of full-size mock-up for 10° section of ITER vacuum vessel thermal shield

In this paper, a full-scale prototype fabrication for vacuum vessel thermal shield (VVTS) of ITER tokamak is described and test results are reported. All the manufacturing processes except for silver coating were performed in the fabrication of 10° section of VVTS. Pre-qualification test was conducted to compare the vertical and the horizontal welding positions. After shell welding, shell distortion was measured and adjusted. Shell thickness change was also measured after buffing process. Specially, VVTS ports need large bending and complex welding of shell and flange. Bending method for the complex and long cooling tube layout especially for the VVTS ports was developed in detail. Dimensional inspection of the fabricated mock-up was performed with a 3D laser scanner and the scanning data was analyzed.

Life Estimation of HVDC Cables Under the Time-Varying Electrothermal Stress Associated With Load Cycles

In this paper, a new procedure is presented for life estimation of HVDC cables subjected to the time-varying electrothermal stress associated with load cycles and voltage. The electric-field inversion phenomenon in the insulation of dc cables is accounted for by updating the field profile as the temperature profile changes with the load. The thermal transients due to load cycles are modeled via the CIGRÉ transient thermal network adapted to dc cables. The life fractions lost during each cycle because of the cyclic variation of the electrothermal stress are computed via an adequate electrothermal life model for the insulation of HVDC cables. The Weibull hypothesis is made for relating cable life to failure probability. The procedure is applied to the load cycles of the prequalification test for HVDC extruded cables after CIGRÉ Technical Brochure 496 that does not consider the effect of thermal and synergistic electrothermal aging. It is thus shown that this test might be less severe than it should be.

Experimental evaluation of cyclically loaded, large-scale, planar and 3-d buckling-restrained braced frames

Buckling-restrained braced frames (BRBFs) are becoming a more common seismic-resisting system in the U.S. BRBs have more equal and stable cyclic axial response than traditional, steel sections which buckle and this makes them attractive for use in seismic applications. Past experiments demonstrating their behavior have tested an isolated BRB and these tests have demonstrated their superior axial behavior. More recent tests, including those summarized in this paper, have tested BRBs in a frame and, unfortunately, those experiments have demonstrated shortcomings of BRBFs. These tests include both planar and 3-dimensional BRBF experiments. The experiments showed that the hysteretic behavior of the BRBFs was very good for moderate inelastic deformations; however severe damage and instabilities may occur at large story drifts. In most cases, these unwanted behavior resulted from inelastic deformation of the beams and columns at the connection. At large story drifts, significant frame damage occurred. This result indicates that BRBs experience significantly different demands in a system than those imposed by simple axial test as required by the BRB prequalification test. This difference should be considered in the connection design and system performance assessment.

Consideration and research of high voltage insulation strategy for ITER Feeder busbar joint

The ITER Feeder busbar joint is an important component which connects different sections of busbar which run from the high temperature superconducting current leads to the magnet terminals. High voltage insulated bus bar sections will be assembled onto the feeder support structure (called the containment duct), and the joints between sections will be made in situ. The high voltage insulation over the joint is the final step to complete the insulation of the whole bus bar system, and its quality is key to achieving the required electrical performance of the system. The final joint has a complex external configuration with an irregular structure in places, which makes it difficult for the application of the insulation. The limited access in the Feeder and the complex joint external structure make the implementation of the joint insulation hard to solve. The Feeder group at ASIPP has carried out significant R&D for the joint insulation, involving research on the selection of materials, the design of the insulation structure, the curing technology and the quality inspection method. After many rounds of manufacturing and testing, the insulation strategy for the Feeder joint will focus on the so-called “wet-winding” technology. Despite the fact that this process has some intrinsic disadvantages, it is more appropriate for the joint structure compared to other methods. The sub-suppliers to ASIPP have chosen this impregnation method for the feeder qualification activities based on guidance from ASIPP. This paper describes the research procedure of the ITER Feeder busbar joint insulation, summarizes the activities on the joint insulation structure design, describes the trials of the impregnation method, and describes the pre-qualification tests. Even for the preferable “wet-winding” process, some improvements have been applied due to recommendations from ITER IO experts. For example, both the use of a vacuum bag during the process and investigation using non-destructive tests (NDT) have been implemented.