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Purpose The purpose of this study is to estimate aerodynamic parameters using regularized regression-based methods. Design/methodology/approach Regularized regression methods used are LASSO, ridge and elastic net. Findings A viable option of aerodynamic parameter estimation from regularized regression-based methods is found. Practical implications Efficacy of the methods is examined on flight test data. Originality/value This study provides regularized regression-based methods for aerodynamic parameter estimation from the flight test data.

Phosphorus is one of the limiting nutrients for crop production, especially in developing countries where soil available P is low. To counter P deficiency, P has been applied at a rate above crop uptake which makes management of P fertilizer a challenge for the scientific community, as high input P can have environmental consequences like eutrophication of water bodies. Physico-chemical and biological methods are widely used for the removal of soluble P from wastewater. Adsorption of P onto a paramagnetic substance like magnetite holds a great promise for its removal and subsequent recovery of adsorbed P. The present study was carried out with the objective of synthesis of magnetite in different molar ratios and its characterization to select the best magnetite material for removal of P. Magnetite was synthesized using the co-precipitation method using ferrous and ferric ions at different molar ratios (1:1, 1:2, 2:1, 5:1) and characterized for Xray diffraction, Fourier transforms infrared spectroscopy, and Brunauer-Emmett-Teller method surface area. All the synthesized material resembled the Joint Committee on Powder Diffraction Standards XRD patterns of reference magnetite and showed strong peaks at 220, 311, 400, 511, and 440 cm-1. FTIR analysis showed the presence of Fe-O bond at 580 cm-1 and characteristic peaks at 1633 and 3400 cm-1 suggesting the presence of a hydroxyl group. Highest surface area (93.001 (m2/g) was observed for magnetite synthesized with a molar ratio of 1:2 (Fe2+/ Fe3+), whereas the surface area of the rest of the synthesized magnetite was close to 50 m2/g. The smallest pore radius was also found in magnetite synthesized with a molar ratio of 1:2 (Fe2+/Fe3+) which contributed to the highest pore volume.

Experimental and numerical analyses are carried out to investigate the influence of twisted tape inserts on the heat transfer and the flow behavior in double tube heat exchangers. First, all the performance factors, namely the Nusselt number, friction factor, and thermal performance factor, were studied for a basic heat exchanger (BHE). Afterwards, twisted tapes with three different twist ratios (7.5, 6, and 4.5) were inserted inside the inner tube of the BHE, which resulted in three different modified heat exchangers (MHEs). For the numerical study, a 3D numerical model is developed with the k-ε RNG turbulent model to visualize the flow and the heat transfer behavior inside the heat exchangers. In both studies, turbulent flow field is maintained, ranging Reynolds number from 15000 to 50000. From the experimental result, an enhanced heat transfer, characterized by the performance factors, is found for all the MHEs compared to the BHE. The most enhanced thermal performance factor is achieved for the MHE with the lowest twist ratio. Finally, a good agreement between obtained numerical and experimental results reveals that the present numerical model can reliably predict the flow and heat transfer behavior in double tube heat exchangers.

The quality changes in Bagda (Penaeus monodon) stored with ice in bamboo and plastic basket for 24 hours immediately after harvest was observed through visual, biochemical and microbial assessments. As indicator of freshness TVB-N and TMA-N were measured at 0h, 12h, and 24h. The concentration of TVB-N ranged from 5.34±0.0212 to 8.045±0.049 mg/100g in bamboo basket and 4±0.0283 to 7.825±0.0354 mg/100g in plastic basket. TMA-N concentration was found as 2.66±0.0141 to 4.045±0.0071 and 1.345±0.0071 to 5.2±0.0424 mg/100g in bamboo and plastic basket respectively. Data indicated that all the values increased with storage time, quality of shrimp started to decline slowly within 24 hours and remained acceptable in both bamboo and plastic baskets even on 24th hour. Standard Plate Count (SPC) of shrimp stored with ice immediately was 0.18×105 and 0.12×105 in bamboo and plastic baskets, respectively. SPC of shrimp stored with ice after 24 hours was 0.17×105 and 0.23×105 in bamboo and plastic baskets, respectively.

The study was carried out to analyse the economics of shifting land from field crops to hog plum cultivation in southern Bangladesh during July to September 2018. A total of 120 farmers were selected by using multistage stratified random sampling technique to collect primary data. Result of the study shows that the per hectare average total cost of hog plum cultivation was Tk. 94,126. The average yield of hog plum was 7.97 t ha-1. Net return from hog plum cultivation was Tk. 126,921 per hectare. By cultivating hog plum, farmers obtained 56 to 93% higher net return than the other existing cropping patterns. Since the BCR (2.94), NPV (Tk. 2215,000) and IRR (59%) were very high, the land shifting decision towards hog plum cultivation was sensible. However, BCR was very low in the initial stages of hog plum plantation. Initial investment support from public or private sector could facilitate the growth of this cultivation practice. Int. J. Agril. Res. Innov. Tech. 10(2): 155-163, December 2020

Bangladesh is one of the most densely populated countries with immense pressure on agricultural land in rural areas. Mainstream of the rural households depend on either agriculture or its associated activities for their livelihood. However, rural land distribution is highly skewed, majority of them are landless. Under such a land scarce situation, farmers in rural areas have been gradually inclining towards land tenancy. Present study steered to explore the nature and volume of temporary land transaction through tenancy agreement in studied areas and to scrutinize its role in aligning land distribution. In 2017, a total of 166 farmers were randomly selected from two different villages in Jashore district for study. Result of the study administrated that land tenancy practice has been significantly mitigating land disparity among rural farmers. Study also explored that comparatively rich farmers are leaning towards tenant out land and most of these lands tenanted in by the landless and marginal farmers. Consequently, on an average landless farm could significantly increases their cultivable land from 0.01 acre to 0.98 acre compared to the marginal farm 0.31 to 0.73 acres. At the same time, cultivable land of medium farm has decreased as of 3.74 acres to 2.83 acres in studied villages. Int. J. Agril. Res. Innov. Tech. 10(2): 164-169, December 2020

Floating gardening acts as a fruitful climate-change adaptation strategy in different wetland areas of Bangladesh. The study accomplished to examine the profitability of floating gardening in Gopalgonj district of Bangladesh in 2018. A total of 100 floating gardeners were interviewed to achieve the objectives. Descriptive statistics and Cobb-Douglas production function were used to investigate the factors influencing yield of floating gardening. The findings reveal that, small and marginal farmers were more involved in floating gardening. Around sixty-five percent of the production costs was contributed by human labour. Floating gardeners of the study area earned a net return of BDT 457,901 per hectare per year. Human labour, fertilizers and support materials significantly affected the yield. More training and improved marketing system could further enhance the profitability. Int. J. Agril. Res. Innov. Tech. 10(1): 87-93, June 2020

This article reports the design, three-dimensional magnetostatic simulation results, coil fabrication, assembly, and low-temperature test results of a C-frame, iron-dominated high-temperature superconductor dipole magnet for ultra high vacuum magnetic-sensitive spectroscopy techniques at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The magnet is required to provide fields up to ~1 T along two spatial directions. With an added capability to rotate about its vertical axis of symmetry, the magnet system is capable of delivering field along all three principal axes. The combination of this magnet and fast-switched, elliptically polarized soft X-rays produced by the NSLS elliptically polarized wiggler forms the basis for an excellent tool for polarization-sensitive studies of magnetic materials. The prototype magnet consists of a set of pancake coils fabricated from BSCCO tape reinforced with stainless steel. Those pancake coils are clamped in a low-carbon AISI 1006 grade steel pole and yoke assembly. For testing purposes, a cold He gas environment provided cooling the superconducting magnet to subtransition temperatures; for operation in an ultra high vacuum endstation environment, cooling can be provided by an external cryocooler. The low-temperature tests establish the safe-operating parameters needed to achieve the target magnetic field values. The measured magnetic field values are in close agreement with the magnetic simulation results, thereby confirming that the magnet design fulfills the performance requirements. The final section of this article lists some suggestions to improve the magnet performance.

Bangladesh is an agrarian country and majority of its population depends on either agriculture or its associated activities. Being a developing country, Bangladesh is characterized by densely populated, widespread unemployment, high incidence of landlessness and labor surplus economy. Under such a land scarce condition, farmers in rural areas have been gradually inclining towards different alternative income generating activities. The study was conducted to assess the nature and extent of occupational diversification, its changes and impacts on household income over time. Data was collected from a selected village, Lebutala in Jashore district of Bangladesh in two different years. In 2000, a total of 107 households were randomly selected which have split and increased to 124 in 2017. Once again, the entire 124 households were interviewed in 2017. Result of the study shows that farmers in the studied area have significant diversity on their income sources. Almost all (94%) of them have dual and 24% of them have multiple occupations. Contributing 40% of the household income, agriculture is still predominant occupation in the rural area. Besides, rural business, dairy farming and self-employed occupations have become more attractive alternatives than the previous time. Result also unveils that the average rural household income (BDT 16,983 per month) has significantly increased over the time. In 2017, more than 61% of the sampled rural household earned above the national rural income level of BDT 13,353 per month. Increases in diversification of income sources were responsible for this enhancement of rural household income. Further diversification is suggested through proper development of small business, dairy farming and selfemployment generating activities in rural areas.

High fat diet (HFD) has been implicated as an independent risk factor for cardiovascular diseases since the second half of the last century. The HFD causes various pathogeneses and progressions of cardiovascular diseases. The oxidative stress and pro-inflammatory reactions induced by the HFD are probably the major risk factors of myocardial damage. In this review we highlight the roles of different dietary fats on cardiovascular diseases and the protective effects of melatonin as a potent antioxidant and anti-inflammation molecule on the pathology induced by HFD. The focus will be given to the molecular mechanisms. The protective effects of melatonin on HFD induced myocardial damage are mediated by multiple pathways. These include that melatonin suppresses the oxidative stress, preserves the normal fat and glucose metabolisms and reduces the pro-inflammatory reactions. Melatonin downregulates the expressions of pro-inflammatory genes of TLR4, NF-κB and NLRP3-Caspase1 but upregulates the expressions of anti-inflammatory genes of Sirt3, CTRP3 and RISK. All of these render melatonin as a powerful protector against cardiovascular diseases caused by the HFD. This review suggests that melatonin can be used as a therapeutic agent in this specific condition.

In the current study, it was found that high fat diet (60% of total kCal) (H) or/and isoproterenol (I) exacerbated oxidative stress and caused myocardial damage. This was indicated by increased levels of LPO, PCO, abnormal mitochondria and altered activities of metabolic as well as antioxidant enzymes in myocardium of rats. Melatonin at different doses (10, 20 and 40 mg/kg) effectively protected against myocardial damage induced by H or/and I and preserved all of these altered parameters. Morphological analyses showed that combination of H and I treatment led to the extensive myofibril disintegration and neutrophil infiltration. Melatonin at the dose of 40 mg/kg almost completely prevented these pathological alterations. The mechanistical studies have uncovered that the protective effects of melatonin on the myocardial damage induced by H and I are attributed to its direct and indirect antioxidative capacity, i.e., it directly scavenges free radicals and also regulates the gene expression of antioxidant enzymes. Collectively, based on the evidences gathered from the current study, it will not be unwise to suggest that melatonin can serve as an ideal therapeutic agent for those cardiovascular diseases caused by oxidative stress.

This paper presents outcome of round robin exercise on usage of ball indentation technique to predict strength properties of three different materials which are used in Indian nuclear reactors. The main objectives were to evolve a standardized procedure of determining the mechanical properties by the Ball Indentation technique and quantification of the variation in strength and fracture properties due to ageing through such tests. Standard uniaxial tensile tests were also carried out to quantify the differences between strength properties predicted by ball indentation and those determined using conventional tests. Three different materials studied were, carbon-manganese steel (Grade: SA 333Gr.6), stainless steel (SA312 Type 304LN) and zirconium alloy (Zr-2.5Nb). The carbon-manganese steel and stainless steel materials were drawn from extruded pipes while Zr-2.5Nb was drawn from pressure tubes, used in Indian Pressurized Heavy Water Reactors. Ball indentation tests were carried out on materials in as received and in aged conditions. The ageing was simulated artificially. The carbon-manganese steel and stainless steels were subjected to cold work while Zr-2.5Nb alloy was subjected to heat treatment at different temperatures with varying hold times and in some cases with charged hydrogen. The round robin exercise was conducted within different research centers of Department of Atomic Energy (DAE), India. This was a blind exercise in which all the conventional tests were carried out by a group (who was not involved in Ball Indentation tests) after the completion of ball indentation tests by participants. The paper presents the prediction of strength properties, using ball indentation, by different participants. The reasons of scatter in the results among the various participants and differences with respect to conventional test results are discussed in the paper.

The polymeric materials used for insulation and sheath in instrumentation and control (I&C) cables of nuclear power plants (NPPs) are subjected to degradation due to various stressors. The prediction of long-term aging and lifetime of cables is generally determined based on accelerated life testing (ALT) experiments which are not only expensive but also time consuming. Application of artificial neural networks (ANNs) in the field of transient diagnosis and condition assessment of electrical and other equipment has been a promising technique; however the use of ANN for reliability prediction of I&C cables has not yet been studied. This paper presents an integrated approach to predict the lifetime and reliability of I&C cables by ANN from the accelerated aging data. In order to validate the proposed methodology for use in probabilistic safety assessment (PSA) of NPP to account for the cable failures, ALT data on a typical cross-linked polyethylene (XLPE) insulated I&C cable has been referred from the literature. The time dependent reliability was predicted by considering the various failure rates. Study demonstrates that by an appropriate training algorithm with suitable network architecture, it is possible to predict the reliability of I&C cables by ANN with the minimal accelerated life testing. (C) 2017 Elsevier Ltd. All rights reserved.

Author(s): Cooley, LD; Ghosh, AK; Dietderich, DR; Pong, I | Abstract: The high-luminosity upgrade of the large hadron collider (HL-LHC) at CERN will replace the main ring inner triplet quadrupoles, identified by the acronym MQXF, adjacent to the main ring intersection regions. For the past decade, the U.S. LHC Accelerator RaD Program, LARP, has been evaluating conductors for the MQXFA prototypes, which are the outer magnets of the triplet. Recently, the requirements for MQXF magnets and cables have been published in [P. Ferracin et al., IEEE Trans. Appl. Supercond., vol. 26, no. 4, Jun. 2016, Art. no. 4000207], along with the final specification for Ti-alloyed Nb3Sn conductor determined jointly by CERN and LARP. This paper describes the rationale beneath the 0.85-mm-diameter strand's chief parameters, which are 108 or more subelements, a copper fraction not less than 52.4%, strand critical current at 4.22 K not less than 631 A at 12 T and 331 A at 15 T, and residual resistance ratio of not less than 150. This paper also compares the performance for ∼100 km production lots of the five most recent LARP conductors to the first 163 km of strand made according to theHL-LHCspecification.Two factors emerge as significant for optimizing performance and minimizing risk: a modest increase of the subelement diameter from 50 to 55 μm, and a Nb:Sn molar ratio of 3.6 instead of 3.4. The statistics acquired so far give confidence that the present conductor can balance competing demands in production for the HL-LHC project.

Author(s): Wang, X; Ambrosio, G; Chlachidze, G; DiMarco, J; Ghosh, AK; Holik, EF; Prestemon, SO; Sabbi, G; Stoynev, SE | Abstract: The U.S. large hadron collider (LHC) Accelerator Research Program, in close collaboration with The European Organization for Nuclear Research (CERN), has developed three generations of high-gradient quadrupole (HQ) Nb3Sn model magnets, to support the development of the 150 mm aperture Nb3Sn quadrupole magnets for the high-luminosity LHC. The latest generation, HQ03, featured coils with better uniformity of coil dimensions and properties than the earlier generations. The HQ03 magnet was tested at fermi national accelerator laboratory (FNAL), including the field quality study. The profiles of low-order harmonics along the magnet aperture observed at 15 kA, 1.9 K can be traced back to the assembled coil pack before the magnet assembly. Based on the measured harmonics in the magnet center region, the coil block positioning tolerance was analyzed and compared with earlier HQ01 and HQ02 magnets to correlate with coil and magnet fabrication. To study the capability of correcting the low-order nonallowed field errors, magnetic shims were installed in HQ03. The expected shim contribution agreed well with the calculation. For the persistent-current effect, the measured a4 can be related to 4% higher in the strand magnetization of one coil with respect to the other three coils. Finally, we compare the field errors due to the interstrand coupling currents between HQ03 and HQ02.

Instrumentation and control (I and C) cables are one of the most important components in nuclear power plants (NPPs) because they provide power to safety-related equipment and also to transmit signals to and from various controllers to perform safety and control functions.

Establishment of rewetting of hot nuclear fuel pins under a pipe break event is an important design aspect of Nuclear Power Plant (NPP). The successful rewetting of heated pins through Emergency Core Cooling System (ECCS) injection stands to be a major requirement as this action mitigates the accident progression. In Advance Heavy Water Reactor (AHWR), ECCS is designed to inject water from a central water rod of the fuel bundle in form of jets to rewet hot surface of fuel pin. This kind of design to reflood the fuel bundle is different than bottom and top spray reflooding practiced in PWR and BWR type of nuclear reactors. The success of the proposed ECCS injection type has been assessed in a separate effect test where the study has been carried out with a simulated single fuel pin. Influence of issuing radial jet on circumferential and axial conduction and associated rewetting pattern has been studied. As ECCS injection may take place at different decay power levels and at different fuel initial temperatures hence experiments are conducted at different power levels (212 W, 600 W, 780 W) and at different initial clad temperatures (400 °C, 600 °C, 660 °C). The injection flow rate has been kept constant at a design flow rate of 1.8 lpm for all the experiments. In all the experiments it is observed that a steep circumferential temperature gradient is established at the beginning of injection and the gradient comes down with the time advancement. A maximum gradient of 500 °C is observed for a short period of time (∼4 s) for the initial temperature of 660 °C. The influence of variation of jet velocity arising from height of it’s injection is reflected on circumferential rewetting velocities which are found to vary from 2 mm/s to 10 mm/s. A correlation developed from experimental data has been proposed to estimate the average fuel temperature at any time instant during rewetting process. The study concludes that the design of multi point injection within the bundle will successfully be able to rewet the simulated fuel pin over the maximum period of time of ∼28.6 s.

The High Luminosity (HiLumi) Large Hadron Collider (LHC) project has, as the main objective, to increase the LHC peak luminosity by a factor five and the integrated luminosity by a factor ten. This goal will be achieved mainly with a new interaction region layout, which will allow a stronger focusing of the colliding beams. The target will be to reduce the beam size in the interaction points by a factor of two, which requires doubling the aperture of the low-β (or inner triplet) quadrupole magnets. The use of Nb3Sn superconducting material and, as a result, the possibility of operating at magnetic field levels in the windings higher than 11 T will limit the increase in length of these quadrupoles, called MQXF, to acceptable levels. After the initial design phase, where the key parameters were chosen and the magnet's conceptual design finalized, the MQXF project, a joint effort between the U.S. LHC Accelerator Research Program and the Conseil Europeen pour la Recherche Nucleaire (CERN), has now entered the construction and test phase of the short models. Concurrently, the preparation for the development of the full-length prototypes has been initiated. This paper will provide an overview of the project status, describing and reporting on the performance of the superconducting material, the lessons learnt during the fabrication of superconducting coils and support structure, and the fine tuning of the magnet design in view of the start of the prototyping phase.

As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build a 150 mm aperture Nb$_{3}$Sn quadrupole for the LHC interaction regions. A first series of 1.5 m long coils were fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new, second-generation, coil design. In this paper we review the main characteristics of the first generation coils, describe the modification in coil lay-out, and discuss their impact on parts design and magnet analysis. As part of the Large Hadron Collider (LHC) Luminosity upgrade program, the U.S.-LHC Accelerator Research Program collaboration and CERN are working together to design and build a 150-mm aperture Nb_3Sn quadrupole for the LHC interaction regions. A first series of 1.5-m-long coils was fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new second-generation coil design. In this paper, we review the main characteristics of the first generation coils, describe the modification in coil layout and discuss their impact on parts design and magnet analysis.

Construction and test results of a 100-mm-bore solenoid made with the high-temperature superconductor (HTS) producing a peak field of over 10 T are presented. This is the first step toward building a very high field solenoid (35-40 T)-one of the key components of the proposed state-of-the-art facility for dark matter search at the Center for Axion and Precision Physics Research, Institute for Basic Science in Korea. The coils made with HTS are expected to provide a field of ~25 T, and the coils made with low-temperature superconductors are expected to provide a field of 10-15 T. REBCO HTS tapes were provided by SuNAM along with the measurements at 20 K in 3.5- to 4-T applied field. The Brookhaven National Laboratory measured several samples at 4 K in the applied field of 4-8 T. This paper will present a series of test results of the conductor, six pancake coils, and the fully assembled solenoid.

To meet critical current density, J$_c$, targets for the Future Circular Collider (FCC), the planned replacement for the Large Hadron Collider (LHC), the high field performance of Nb$_3$Sn must be improved, but champion J$_c$ values have remained static for the last 10 years. Making the A15 phase stoichiometric and enhancing the upper critical field H$_{c2}$ by Ti or Ta dopants are the standard strategies for enhancing high field performance but detailed recent studies show that even the best modern wires have broad composition ranges. To assess whether further improvement might be possible, we employed EXAFS to determine the lattice site location of dopants in modern high-performance Nb$_3$Sn strands with J$_c$ values amongst the best so far achieved. Although Ti and Ta primarily occupy the Nb sites in the A15 structure, we also find significant Ta occupancy on the Sn site. These findings indicate that the best performing Ti-doped stand is strongly sub-stoichiometric in Sn and that antisite disorder likely explains its high average H$_{c2}$ behavior. These new results suggest an important role for dopant and antisite disorder in minimizing superconducting property distributions and maximizing high field J$_c$ properties., 14 pages, 6 figures

Instrumentation and control (I&C) cables used in nuclear power plants (NPPs) are exposed to various deteriorative environmental effects during their operational lifetime. The factors consisting of long-term irradiation (at rather low dose rates, in the presence of oxygen), and enhanced temperature eventually result in insulation degradation. Monitoring of the actual state of the cable insulation and the prediction of their residual service life consist of the measurement of the properties that are directly proportional to the functionality of the cables [usually the elongation at break (EAB) is used as the critical parameter]. Although, there exist several condition monitoring and life estimation techniques, currently there is no any standard methodology or an approach towards incorporating cable ageing effects into probabilistic safety assessment of NPPs. In view of this, accelerated thermal and radiation ageing of I&C cable insulation materials have been carried out and the degradation due to thermal and radiation ageing has been assessed using oxidation induction time and oxidation induction temperature measurements by differential scanning calorimetry (DSC). As EAB is considered to be a benchmark characterization technique for polymeric materials, tensile tests have also been carried out on these cable materials for correlating the DSC findings with EAB. The scanning electron microscopy (SEM) performed on fresh and aged samples support relatively good correlation between thermal and mechanical properties.

Currently the ductile fracture assessment of cracked pipes, under earthquake loading, is based on the monotonic J – R curve where the earthquake load is considered as a one-time applied load monotonically increasing to its maximum magnitude. The cyclic nature of earthquake load and associated cyclic-tearing damage (or cyclic J – R curve) is not explicitly considered. A series of cyclic-tearing and monotonic fracture tests is performed on circumferential through-wall-cracked pipes and pipe welds (five material categories) which are used in Indian Nuclear Power Plants (NPPs) piping system. The fracture behaviour of these pipes under cyclic loading vis-a-vis monotonic loading has been studied. The cyclic J – R curves of all material categories are significantly lower than the monotonic J – R curves and found strongly dependent on the applied load-history. Hence, cyclic J – R curve shall be evaluated for the load-history which is consistent with plant site (anticipated seismic loading), piping system layout and the crack location. The maximum moment observed during cyclic loading test is lower by a small to moderate amount than that obtained in the monotonic fracture tests on identical pipe. A relation has been obtained for cracked pipes which assesses if large crack growth/tearing would take place under displacement-controlled cyclic loading.

Persistent magnetization currents are induced in superconducting filaments during the current ramping in magnets. The resulting perturbation to the design magnetic field leads to field quality degradation, particularly at low field, where the effect is stronger relative to the main field. The effects observed in NbTi accelerator magnets were reproduced well with the critical-state model. However, this approach becomes less accurate for the calculation of the persistent-current effects observed in Nb 3 Sn accelerator magnets. Here, a finite-element method based on the measured strand magnetization is validated using three state-of-the-art Nb 3 Sn accelerator magnets featuring different subelement diameters, conductor critical currents, magnet designs, and test temperatures. The temperature dependence of the persistent-current effects is reproduced. Based on the validated model, the impact of conductor design on the persistent-current effects is discussed. The strengths, limitations, and possible improvements of the approach are also discussed.

The HQ magnet is a 120 mm aperture, 1-meter-long Nb$_{3}$Sn quadrupole developed by the LARP collaboration in the framework of the High-Luminosity LHC project. A first series of coils was assembled and tested in 5 assemblies of the HQ01 series. The HQ01e model achieved a maximum gradient of 170 T/m at 4.5 K at LBNL in 2010-2011 and reached 184 T/m at 1.9 K at CERN in 2012. A new series of coils incorporating major design changes was fabricated for the HQ02 series. The first model, HQ02a, was tested at Fermilab where it reached 98% of the short sample limit at 4.5 K with a gradient of 182 T/m in 2013. However, the full training of the coils at 1.9 K could not be performed due to a current limit of 15 kA. Following this test, the azimuthal coil pre-load was increased by about 30 MPa and an additional current lead was installed at the electrical center of the magnet for quench protection studies. The test name of this magnet changed to HQ02b. In 2014, HQ02b was then shipped to CERN as the first opportunity for full training at 1.9 K. In this paper, we present a comprehensive summary of the HQ02 test results including: magnet training at 1.9 K with increased pre-load, quench origin and propagation, and ramp rate dependence. A series of powering tests was also performed to assess changes in magnet performance with a gradual increase of the MIITs. We also present the results of quench protection studies using different setting for detection, heater coverage, energy extraction and the Coupling-Loss Induced Quench (CLIQ) system.

Next-generation particle accelerators, such as the proposed Large Hadron Collider (LHC) energy upgrade (highenergy LHC), will require very-high-field (> 20 T) superconducting magnets. This paper describes the progress toward this goal made to date as a part of a collaborative work between Particle Beam Lasers, Inc., and Brookhaven National Laboratory. To reduce the cost, high-temperature superconductors (HTSs) are used in a hybrid design with conventional low-temperature superconductors (LTSs) Nb3Sn and NbTi. The focus of this paper is on using a second generation (2G) ReBCO HTS tape in cosine-theta coil geometry. The complex ends of the cosine-theta geometry are particularly challenging for a brittle HTS tape. We report the construction and 77-K test results, one with a 4-mm and another with a 12-mm ReBCO tape, neither showing measurable degradation. This paper also presents the first successful use of Kapton CI on an HTS tape, which offers many advantages. Future plans include the construction and 4-K testing of a full cosine-theta HTS coil (first in a stand-alone mode and then in a hybrid structure with LTS coils) and the modeling and measurements of magnetization. This paper is a part of comprehensive research and development toward eventually building a high-field accelerator-quality dipole magnet.

The development of $Nb_3Sn$ quadrupole magnets for the High-Luminosity LHC upgrade is a joint venture between the US LHC Accelerator Research Program (LARP)* and CERN with the goal of fabricating large aperture quadrupoles for the LHC in-teraction regions (IR). The inner triplet (low-β) NbTi quadrupoles in the IR will be replaced by the stronger Nb$_{3}$Sn magnets boosting the LHC program of having 10-fold increase in integrated luminos-ity after the foreseen upgrades. Previously LARP conducted suc-cessful tests of short and long models with up to 120 mm aperture. The first short 150 mm aperture quadrupole model MQXFS1 was assembled with coils fabricated by both CERN and LARP. The magnet demonstrated strong performance at the Fermilab’s verti-cal magnet test facility reaching the LHC operating limits. This paper reports the latest results from MQXFS1 tests with changed pre-stress levels. The overall magnet performance, including quench training and memory, ramp rate and temperature depend-ence, is also summarized. The development of Nb$_{3}$Sn quadrupole magnets for the High-Luminosity LHC upgrade is a joint venture between the US LHC Accelerator Research Program (LARP)* and CERN with the goal of fabricating large aperture quadrupoles for the LHC interaction regions (IR). The inner triplet (low-β) NbTi quadrupoles in the IR will be replaced by the stronger Nb$_{3}$Sn magnets boosting the LHC program of having 10-fold increase in integrated luminosity after the foreseen upgrades. Previously, LARP conducted successful tests of short and long models with up to 120 mm aperture. The first short 150 mm aperture quadrupole model MQXFS1 was assembled with coils fabricated by both CERN and LARP. The magnet demonstrated a strong performance at Fermilab's vertical magnet test facility reaching the LHC operating limits. This paper reports the latest results from MQXFS1 tests with changed prestress levels. The overall magnet performance, including quench training and memory, ramp rate, and temperature dependence, is also summarized.

The U.S. LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb3Sn magnets for the high-luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb 3Sn quadrupoles for the LHC interaction regions. These magnets will replace the present 70-mm-aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity up to 5 × 1034 cm –2s–1 or more. Over the past decade, LARP successfully fabricated and tested short and long models of 90 and 120-mm-aperture Nb3Sn quadrupoles. Recently, the first short model of 150-mm-diameter quadrupole MQXFS was built with coils fabricated both by LARP and CERN. The magnet performance was tested at Fermilab's vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence, as well as protection heater studies.

The US LHC Accelerator Research Program is constructing prototype interaction region quadrupoles as part of the US in-kind contribution to the Hi-Lumi LHC project. The low-beta MQXFA Q1/Q3 coils have a 4-m length and a 150 mm bore. The design is first validated on short, one meter models (MQXFS) developed as part of the longstanding Nb$_{3}$Sn quadrupole R&D; by LARP in collaboration with CERN. In parallel, facilities and tooling are being developed and refined at BNL, LBNL, and FNAL to enable long coil production, assembly, and cold testing. Long length scale-up is based on the experience from the LARP 90 mm aperture (TQ-LQ) and 120 mm aperture (HQ and Long HQ) programs. A 4-m long MQXF practice coil was fabricated, water jet cut and analyzed to verify procedures, parts, and tooling. In parallel, the first complete prototype coil (QXFP01a) was fabricated and assembled in a long magnetic mirror, MQXFPM1, to provide early feedback on coil design and fabrication following the successful experience of previous LARP mirror tests.

In-service inspections of many nuclear power plants have revealed that cracks are most likely to occur in a weld or in the regions near the weld. In part-I, the problem of a stationary crack lying at the centre of a weld in a pure bending specimen SE(PB) was analysed. The detailed structure of the global plastic fields for a deep crack, under fully plastic condition, was presented. Aspects related to the state of stress at the base-weld interface were discussed. To enhance our understanding of the weld strength mismatch effects, other commonly used fracture specimens, that is, compact tension C(T) and middle tension M(T) specimens having a weld centre crack were analysed in the present investigation. The influence of weld mismatch on the structure of global stress fields (leading to plastic yielding of the ligament) as well as on the crack tip constraint was studied. It is demonstrated that, when a crack is postulated at the centre of a weld, a family of stress fields proposed in part-I for a SE(PB) specimen is applicable to a C(T) specimen also. The studies performed in this article, along with part-I, have established that in comparison to slip line field analysis, the modified upper bound theorem is simple and more general. It is applicable to macroscopically homogeneous materials and can also account for weld mismatch effects.

Currently leak-before-break based design and fracture stability assessment considers the earthquake as once applied non-cyclic load, which monotonically increases up to its maximum magnitude. The cyclic character of earthquake load and associated cyclic tearing failure mode (tearing–fatigue regime) are not explicitly considered while demonstrating stability of a through wall cracked pipe. To single out and quantify the impact of cyclic tearing on fracture stability of circumferential through wall cracked pipes, a systematic programme involving extensive number of tests is carried out. The load reduction factors (β) or safety margins, required to ensure cracked pipe stability for specified number of reversible load cycles, are directly evaluated from cyclic and corresponding monotonic pipe tests. They are presented as Cyclic Tearing Failure Assessment Diagram (CTFAD) and a β-factor equation. The proposed β-factors when applied on the monotonic critical load of a cracked pipe (evaluated using existing procedures/methods) will ensure its fracture integrity for specified number of load cycles. The safety margin required against cyclic fracture instability under different levels of earthquakes is presented.

Large-aperture, high-field, Nb3Sn quadrupoles are being developed by the U.S. LHC accelerator research program (LARP) for the High luminosity upgrade of the Large Hadron Collider (HiLumi-LHC). The first 1 m long, 120 mm aperture prototype, HQ01, was assembled with various sets of coils and tested at LBNL and CERN. Based on these results, several design modifications have been introduced to improve the performance for HQ02, the latest model. From the field quality perspective, the most relevant improvements are a cored cable for reduction of eddy current effects, and more uniform coil components and fabrication processes. This paper reports on the magnetic measurements of HQ02 during recent testing at the Vertical Magnet Test Facility at Fermilab. Results of baseline measurements performed with a new multilayer circuit board probe are compared with the earlier magnet. An analysis of probe and measurement system performance is also presented.