Cryogenics最新文献

{"title":"Quantitative analysis of the impact of room temperature stability on cryostat performance","authors":"Siqi Liu ,&nbsp;Xiangjie Kong ,&nbsp;Haiyang Zhang ,&nbsp;Bo Gao ,&nbsp;Huilun Jia ,&nbsp;Zongwei Han","doi":"10.1016/j.cryogenics.2024.103974","DOIUrl":"10.1016/j.cryogenics.2024.103974","url":null,"abstract":"<div><div>The constant temperature in laboratories is crucial for precise low-temperature measurements. Currently, there are no reports on the specific temperature needs for such experiments or quantitative analyses of how room temperature fluctuations affect cryostat control. This paper proposes a method to quantitatively analyze these fluctuations and their impact on cryostat temperature control. Taking the cryostat using for 2 K-5 K thermodynamic temperature measurement as the research object, and conducts model simulation and experimental validation. The research results indicate the primary influence on the sphere’s temperature is the time-dependent fluctuation of the room temperature. As temperature fluctuations propagate from the cryostat’s outer casing to the sphere, heat conduction is the dominant factor. The temperature fluctuations inside the system caused by environmental temperature fluctuations can be quantitatively expressed by a simple linear formula, with the coefficient being the fluctuation attenuation rate, which is 6.590 × 10^-4 in this system. The deviation between experimental results and simulation results is within 5 %. To keep the sphere’s ambient temperature influence below 0.077mK, or 20 % of cryocooler-induced fluctuations, the room temperature must be controlled within 0.12 °C. In addition, the fluctuation period of room temperature is controlled below 1 h, the 0th flange is thickened, the rod is lengthened, and the material of the rod is changed to G10 above 4.2 K and stainless steel below 4.2 K can also effectively attenuate the influence on system temperature control.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103974"},"PeriodicalIF":1.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on AC loss of stacked REBCO cable wrapped with magnetic strip","authors":"Wei Chen ,&nbsp;Rong Jin ,&nbsp;Fei Chi ,&nbsp;Yunyang Ye ,&nbsp;Wenan Wang ,&nbsp;Xinsheng Yang ,&nbsp;Yunpeng Zhu ,&nbsp;Lijun Cai ,&nbsp;Xiaguang Sun ,&nbsp;Xiaojuan Li","doi":"10.1016/j.cryogenics.2024.103975","DOIUrl":"10.1016/j.cryogenics.2024.103975","url":null,"abstract":"<div><div>REBCO stacked cables have great potential for application in high-temperature superconducting (HTS) power devices due to their compact structure and easy scalability. However, when the cable runs in an alternating external field, it will generate AC losses, and excessive AC losses will increase the cooling cost and even cause the cable quench. This article proposes a magnetic material wrapped REBCO cable that can effectively reduce the AC loss of the cable under external magnetic fields. Firstly, the AC losses of REBCO cables wrapped with magnetic and non-magnetic materials were compared under different strength external fields. The results showed that cables wrapped with strong magnetic materials had lower AC losses. Secondly, the AC losses of cables prepared with strong magnetic wrapping materials of different thicknesses were studied under different external fields. The results showed that the thicker the magnetic material, the more significant the reduction in AC losses of the cable. Overall, this article presents new analysis and results that are useful for future design of HTS cables.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103975"},"PeriodicalIF":1.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and analysis of a HTS internally cooled cable for the Muon Collider target and capture solenoid magnets","authors":"L. Bottura ,&nbsp;C. Accettura ,&nbsp;A. Kolehmainen ,&nbsp;J. Lorenzo Gomez ,&nbsp;A. Portone ,&nbsp;P. Testoni","doi":"10.1016/j.cryogenics.2024.103972","DOIUrl":"10.1016/j.cryogenics.2024.103972","url":null,"abstract":"<div><div>The Muon Collider is one of the options considered as the next step in High Energy Physics. It bears many challenges, last not least in superconducting magnet technology. The target and capture solenoid is one of them, a channel of approximately 18 m length consisting of co-axial solenoid magnets with a 1.2 m free bore and peak field on axis of 20 T. One of the main concerns come from the nuclear radiation environment that may influence the stable operation of the coil, as well as its material integrity. Energetic photons cause large radiation heat load, of the order of several kW in the cold mass, and deposit a considerable dose, several tens of MGy. Neutrons cause material damage, at the level of 10^-3 DPA. These values are at the present limit of superconducting coil technology. We describe here the conceptual design of the target and capture solenoid, focusing on the HTS cable design, which is largely inspired by the VIPER concept developed at MIT. We show how to address margin and protection, cooling and mechanics specific to the HTS cable selected.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103972"},"PeriodicalIF":1.8,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AC loss and shielding in stacks of coated conductors: Analytic modelling and comparison to experiment","authors":"M.D. Sumption ,&nbsp;C. Ebbing ,&nbsp;G. Panasyuk ,&nbsp;C. Kovacs ,&nbsp;G.J.P. Murphy ,&nbsp;T. Haugan ,&nbsp;E.W. Collings","doi":"10.1016/j.cryogenics.2024.103963","DOIUrl":"10.1016/j.cryogenics.2024.103963","url":null,"abstract":"<div><div>This work explores the effects of the stacking of coated conductor tapes on their AC loss and penetration fields (<em>B_p</em>). The penetration field <em>B_p</em> and AC loss of short lengths of coated conducted tape stacks are analyzed, measured, and compared to a simple analytic model. The tape widths (<em>w</em>) and number of tapes in the stacks (<em>N_s</em>) were 4 mm (<em>N_s</em> = 1, 3, 5, series-305) and 12 mm (<em>N_s</em> = 1–40, series-244). Experimentally, the losses of the series-244 and series-305 tape stacks were measured in a spinning magnet calorimeter (SMC) in which the samples are exposed to a spinning field of frequency, <em>f</em>, up to 110 Hz and amplitude <em>B₀</em> = 566 mT and the power is measured by a calibrated boil-off calorimeter. These results were compared to calculated loss as a function of <em>N_s</em> for both tapes. In addition, the calculated <em>B_p</em> was plotted vs <em>N_s</em>. The basic effect observed was that stacking coated conductor tapes tended to form an effective composite with an increase <em>B_p,comp</em> and modified loss (For <em>B₀</em> &lt; <em>B_p,comp</em>, <em>P_tot</em> was reduced with <em>N_s,</em> the effect saturating for <em>N_s</em> &gt; 20). This could be understood in terms of treating a stack of conductors as a composite described in terms of a Brandt equations applied to a dilute superconductor. The results show and model the significantly reduced loss that stacks of conductors can have significantly for moderate levels of applied field. Such results are directly transferrable to cables of stacked strands.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103963"},"PeriodicalIF":1.8,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The thermal performance model of a 105 [email protected] K 4He Joule-Thomson cryocooler designed for space applications","authors":"Ziyao Liu ,&nbsp;Bin Yang ,&nbsp;Zijie Pan ,&nbsp;Yuexue Ma ,&nbsp;Jianguo Li ,&nbsp;Jia Quan ,&nbsp;Yanjie Liu ,&nbsp;Guotong Hong ,&nbsp;Jingtao Liang","doi":"10.1016/j.cryogenics.2024.103965","DOIUrl":"10.1016/j.cryogenics.2024.103965","url":null,"abstract":"<div><div>The ⁴He Joule-Thomson cryocooler (JTC) ensures the operation of space detectors working within the 4 K temperature range, such as the Block Impurity Band Infrared Detector (BIBID). In addition, the ⁴He JTC is one of the essential components of the 300 K to 50 mK space cryochain. It can precool sub-Kelvin refrigerators, such as the adiabatic demagnetization refrigerator (ADR) and the dilution refrigerator (DR). With the development of space science, the need for cooling power at the 4 K temperature range is growing. Thus, a thermal performance model of the ⁴He JTC precooled by a two-stage thermally coupled pulse tube cryocooler (PTC) is designed, manufactured, and tested with an eye toward space applications. A four-stage compression system with a high operating frequency and large pistons is designed and used to drive the JT cycle. This ⁴He JTC has a total mass of 55 kg and can provide a cooling capacity of 105 mW at 4.41 K with a total input electric power of 548 W.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103965"},"PeriodicalIF":1.8,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Helium circulation cooling experiment for a 3T NbTi superconducting magnet","authors":"Zhiming Bai ,&nbsp;Jing Li ,&nbsp;Xinhui Cui ,&nbsp;Gang Yang","doi":"10.1016/j.cryogenics.2024.103964","DOIUrl":"10.1016/j.cryogenics.2024.103964","url":null,"abstract":"<div><div>This paper proposes an experimental investigation to validate the use of helium as the sole coolant in a pipe circulation cooling mode for a small 3 T NbTi superconducting magnet. Injecting helium into pipes and liquefying the magnet at 4.2 K will also be explored, utilizing the evaporation of small amounts of liquid helium within the pipes to cool the NbTi magnet and calculate its liquefaction volume and cooling time. Firstly, we investigated a novel approach to achieve acceptable temperatures for current leads by augmenting the top mass and increasing the length of the leads. Additionally, stainless steel (SS) loop tubes surrounding the magnet were designed in a new way to enhance convective heat exchange. Finally, various heat conduction devices were added and after successfully cooling all parts of the experimental apparatus, the heat transfer formula will be used to calculate the theoretical cooling time of pulsed supplementary helium gas, which will then be compared and discussed with actual experimental time. The cryogenic experiment shows that less liquid helium without any other coolants can be adopted efficiently to cool LTS magnets by SS pipelines. Consequently, this approach is significant to reducing consumption of coolant for cooling the LTS NbTi magnet to 4.2 K.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103964"},"PeriodicalIF":1.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel numerical simulation approach for cryogenic CO2 frosting in binary mixture gas by integrating desublimation and gas-solid phase equilibrium models","authors":"Tianbiao He ,&nbsp;Min Zhou ,&nbsp;Jinyang Han ,&nbsp;Meng Qi ,&nbsp;Ning Mao","doi":"10.1016/j.cryogenics.2024.103958","DOIUrl":"10.1016/j.cryogenics.2024.103958","url":null,"abstract":"<div><div>Cryogenic CO₂ separation from natural gas is a promising technology due to its environmental benefits and smaller spatial requirement. Nonetheless, the dynamics of CO₂ desublimation and subsequent frost layer formation under cryogenic conditions for natural gas pre-treatment remain largely unexplored. Addressing this gap, this paper presents a novel numerical simulation approach by integrating desublimation phase change model and vapor-solid phase equilibrium model to investigate CO₂ frost layer formation on the cold wall, revealing that both the cold wall temperature and the initial CO₂ concentration significantly influence the thickness of the CO₂ frost layer. Moreover, the study finds that the density of frost layer intensifies over time, with the highest density observed near the cold surface. Furthermore, increasing the cold wall temperature and the flow rate not only increases the average density of the CO₂ frost layer but also affects the outlet CO₂ concentration. To adhere to specific outlet CO₂ concentration targets and desublimation duration, it is critical to adjust the cold wall temperature and the inlet flow velocity dynamically. Therefore, cryogenic CO₂ removal methods, by reducing the spatial requirements of CO₂ pre-treatment units, offer a practical and efficient solution for small-scale natural gas liquefaction plants. This approach not only facilitates operational efficiency but also contributes to the broader effort of mitigating greenhouse gas emissions, aligning with environmental sustainability objectives.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103958"},"PeriodicalIF":1.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bundle effect on a helical coil in liquid nitrogen with pool boiling for liquid oxygen densification","authors":"Mansu Seo ,&nbsp;Sejin Kwon","doi":"10.1016/j.cryogenics.2024.103962","DOIUrl":"10.1016/j.cryogenics.2024.103962","url":null,"abstract":"<div><div>The need to densify oxidizers using cryogenic fluids is increasing to enhance the performance of launch vehicles. One of the most practical methods for oxidizer densification is heat exchange cooling between liquid oxygen and liquid nitrogen, typically using a tube bundle heat exchanger. Due to the multiple tubes in the bundle, a bundle effect arises, which enhances convective heat transfer by inducing liquid agitation from bubble generation and rising. This paper presents experimental results and prediction models that account for bubble behavior in a tube bundle. The experiment is conducted with saturated liquid nitrogen in a pool at atmospheric pressure and helical coil-type heat exchangers instead of a traditional tube bundle stack heat exchanger. Liquid oxygen densification is achieved by varying mass flow rates and inlet temperatures. Single-passage helical coils made of copper are used to minimize uncertainty from maldistribution flow and reduce thermal resistance compared to convective heat transfer coefficients in the inner and outer tubes. The coils, with an outer diameter of 12.7 mm, were tested in both vertical and horizontal directions and with various coil pitches. The bundle effect was clearly observed under helical coil conditions, and the experiment confirmed that the convective heat transfer coefficient increased with increasing heat flux and bubble generation rate. The prediction models considering bubble behavior—rising and generation rate—were validated by comparison with experimental results. The forced convective Nusselt number, experimentally measured to range from 23 to 361 through its correlation with the Boiling Reynolds number, closely followed the predicted correlation curve of the bubble generation model. It demonstrated a mean absolute error of 83.3, a standard deviation of 65.6, and an average relative error of 64.8 %. These values show improved accuracy compared to the relative errors of two predicted curves in the bubble rising model: 216 % for the single circular tube correlation and 381 % for tube bank correlations. This improvement suggests that the increased bubble generation rate with heat flux is better reflected for liquid oxygen densification with a helical coil submerged in large-scale static pool condition.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103962"},"PeriodicalIF":1.8,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2D mechanical representation of superconducting magnets: A comparative study of plane stress and plane strain","authors":"N. Sala ,&nbsp;A. Bersani ,&nbsp;M. Bracco ,&nbsp;B. Caiffi ,&nbsp;S. Farinon ,&nbsp;A. Gagno ,&nbsp;F. Levi ,&nbsp;D. Novelli ,&nbsp;R. Musenich ,&nbsp;A. Pampaloni ,&nbsp;M. Sorbi ,&nbsp;R.U. Valente","doi":"10.1016/j.cryogenics.2024.103956","DOIUrl":"10.1016/j.cryogenics.2024.103956","url":null,"abstract":"<div><div>When approaching the mechanical design of a superconducting magnet, whenever possible the starting model is a 2D approximation. If rotational symmetry (solenoid-like winding) is present, the 2D representation is unique and contains no approximations. If, on the other hand, a non-axisymmetric system is opted for, the 2D representation is not unique and there are main options available, as plane stress, plane stress with thickness, plane strain and generalized plane strain. Considering z as the direction normal to the 2D plane, the plane stress option defines a stress state in which no normal or shear stresses perpendicular to the xy plane can occur (<span><math><msub><mrow><mi>σ</mi></mrow><mrow><mi>z</mi></mrow></msub><mo>=</mo><msub><mrow><mi>σ</mi></mrow><mrow><mi>x</mi><mi>z</mi></mrow></msub><mo>=</mo><msub><mrow><mi>σ</mi></mrow><mrow><mi>y</mi><mi>z</mi></mrow></msub><mo>=</mo><mn>0</mn></math></span>). In this option, deformation can occur in the thickness direction of the element, which will become thinner when stretched and thicker when compressed; it is generally used for objects with limited depth (thin objects).</div><div>In contrast, plane strain refers to the fact that deformation can only occur in plane, which means that no out-of-plane deformation will occur (<span><math><msub><mrow><mi>ϵ</mi></mrow><mrow><mi>z</mi></mrow></msub><mo>=</mo><msub><mrow><mi>ϵ</mi></mrow><mrow><mi>x</mi><mi>z</mi></mrow></msub><mo>=</mo><msub><mrow><mi>ϵ</mi></mrow><mrow><mi>y</mi><mi>z</mi></mrow></msub><mo>=</mo><mn>0</mn></math></span>). The plane strain option is generally appropriate for structures of nearly infinite length, relative to their cross section, that exhibit negligible length changes under load. The “generalized plane strain” option imposes the axial strain equal to a constant value; this condition does not reproduce the real operating condition of the magnet and is therefore excluded. The “plane stress with thickness” uses the same equations as the plane stress option but, output quantities are given per unit length defined with thickness; therefore, it is again excluded from the comparison. Superconducting magnets, such as dipoles, do not fit neatly into any of the above options: they are far from thin but deform longitudinally under load. This work reports a comparative study of plane stress and plane strain in the specific case study of a dipole magnet.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103956"},"PeriodicalIF":1.8,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large cryogenic magnetocaloric effect in Na5Gd4F(SiO4)4","authors":"Zuhua Chen ,&nbsp;Shilin Yu ,&nbsp;Guochun Zhang ,&nbsp;Changkun Wang ,&nbsp;Jiahao Gao ,&nbsp;Yicai Zhang ,&nbsp;Yanan Zhao ,&nbsp;Zhenxing Li ,&nbsp;Jun Shen ,&nbsp;Heng Tu","doi":"10.1016/j.cryogenics.2024.103955","DOIUrl":"10.1016/j.cryogenics.2024.103955","url":null,"abstract":"<div><div>The adiabatic demagnetization refrigeration based on the magnetocaloric effect of magnetic materials has been regarded as an effective technology to attain sub-Kelvin temperature. In this article, the magnetic properties and MCE of Na₅Gd₄F(SiO₄)₄ compound are investigated. Due to the high Gd³⁺ ion/anion ligand ratio and weak magnetic interaction, Na₅Gd₄F(SiO₄)₄ exhibits a large magnetic entropy change of 49.6 J·kg⁻¹·K⁻¹ under magnetic field change of 0–7 T at 2.6 K, which surpasses the commercial magnetic refrigerant Gd₃Ga₅O₁₂ under the same conditions. Besides, its refrigeration capacity and the relative cooling power under magnetic field change of 0–7 T reaches up to 308.9 J·kg⁻¹ and 406.7 J·kg⁻¹, respectively. These properties indicate that Na₅Gd₄F(SiO₄)₄ compound is a promising magnetic refrigeration material.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"143 ","pages":"Article 103955"},"PeriodicalIF":1.8,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}