Improvement of lower hybrid current drive systems for high-power and long-pulse operation on EAST

Wang M.,Liu L.,Zhao L.M.,Li M.H.,Ma W.D.,Hu H.C.,Wu Z.G.,Feng J.Q.,Yang Y.,Zhu L.,Chen M.,Zhou T.A.,Jia H.,Zhang J.,Cao L.,Zhang L.,Liang R.R.,Ding B.J.,Zhang X.J.,Shan J.F.,Liu F.K.,Ekedahl A.,Gonich 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m2 . Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 C, much below the permissible value of tungsten material (~1200 C). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-activemultijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5 toroidally from the 4.6 GHz LH system and is not magnetically connected

In-situ high-energy synchrotron X-ray diffraction study of micromechanical behavior of multiple phases in Ni₄₇Ti₄₄Nb₉ shape memory alloy

Sun, G.A.,Wang, X.L.,Wang, Y.D.,Woo, W.C.,Wang, H.,Liu, X.P.,Chen, B.,Fu, Y.Q.,Sheng, L.S.,Ren, Y. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.560 No.-

High-energy synchrotron X-ray diffraction technique was used to in-situ characterize microstructure, lattice strain, and phase transition behavior of a Ni<SUB>47</SUB>Ti<SUB>44</SUB>Nb<SUB>9</SUB> shape memory alloy. Phase transformation kinetics and deformation mechanisms were studied under a uniaxial tension at three testing temperatures, i.e., -70<SUP>o</SUP>C, 25<SUP>o</SUP>C, and 150<SUP>o</SUP>C. At a testing temperature of -70<SUP>o</SUP>C, a complicated phase transformation with four stages of micromechanical deformation was identified which is associated with changes of martensite substructures. At room temperature of 25<SUP>o</SUP>C, there was no stress-induced selection process of variants of B19' phases observed. Whereas at a testing temperature of 150<SUP>o</SUP>C, there was no any phase transformation observed. It is verified that β-Nb phase, an effective stabilizer for the austenite, delays the process of martensitic transformation and relaxes the strain energy without strengthening the matrix. This new finding is important to understand the relationship between the micromechanical deformation behavior and phase transformations in the Ni<SUB>47</SUB>Ti<SUB>44</SUB>Nb<SUB>9</SUB> SMA.

Search forB0→pΛ¯π−γat Belle

Lai, Y.-T.,Wang, M.-Z.,Adachi, I.,Aihara, H.,Asner, D. M.,Aulchenko, V.,Aushev, T.,Bakich, A. M.,Bala, A.,Bhuyan, B.,Bobrov, A.,Bozek, A.,Brač,ko, M.,Browder, T. E.,Chang, P.,Chekelian, V.,Chen, American Physical Society 2014 PHYSICAL REVIEW D - Vol.89 No.5

<P>We search for the charmless B-o decay with final state particles p (Lambda) over bar pi(-)gamma using the full data sample that contains 772 x 10(6)B (B) over bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. This decay is predicted to proceed predominantly via the b -> s gamma radiative penguin process with a high energy photon. No significant signal is found. We set an upper limit of 6.5 x 10(-7) for the branching fraction of B-o -> p (Lambda) over bar pi(-)gamma at the 90% confidence level.</P>

Association of two independent functional risk haplotypes in <i>TNIP1</i> with systemic lupus erythematosus

Adrianto, Indra,Wang, Shaofeng,Wiley, Graham B.,Lessard, Christopher J.,Kelly, Jennifer A.,Adler, Adam J.,Glenn, Stuart B.,Williams, Adrienne H.,Ziegler, Julie T.,Comeau, Mary E.,Marion, Miranda C.,Wa Wiley Subscription Services, Inc., A Wiley Company 2012 Vol.64 No.11

<P><B>Abstract</B></P><P><B>Objective</B></P><P>Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production and altered type I interferon expression. Genetic surveys and genome‐wide association studies have identified >30 SLE susceptibility genes. One of these genes, <I>TNIP1</I>, encodes the ABIN1 protein. ABIN1 functions in the immune system by restricting NF‐κB signaling. The present study was undertaken to investigate the genetic factors that influence association with SLE in genes that regulate the NF‐κB pathway.</P><P><B>Methods</B></P><P>We analyzed a dense set of genetic markers spanning <I>TNIP1</I> and <I>TAX1BP1</I>, as well as the <I>TNIP1</I> homolog <I>TNIP2</I>, in case–control populations of diverse ethnic origins. <I>TNIP1</I>, <I>TNIP2</I>, and <I>TAX1BP1</I> were fine‐mapped in a total of 8,372 SLE cases and 7,492 healthy controls from European‐ancestry, African American, Hispanic, East Asian, and African American Gullah populations. Levels of <I>TNIP1</I> messenger RNA (mRNA) and ABIN1 protein in Epstein‐Barr virus–transformed human B cell lines were analyzed by quantitative reverse transcription–polymerase chain reaction and Western blotting, respectively.</P><P><B>Results</B></P><P>We found significant associations between SLE and genetic variants within <I>TNIP1</I>, but not in <I>TNIP2</I> or <I>TAX1BP1</I>. After resequencing and imputation, we identified 2 independent risk haplotypes within <I>TNIP1</I> in individuals of European ancestry that were also present in African American and Hispanic populations. Levels of <I>TNIP1</I> mRNA and ABIN1 protein were reduced among subjects with these haplotypes, suggesting that they harbor hypomorphic functional variants that influence susceptibility to SLE by restricting ABIN1 expression.</P><P><B>Conclusion</B></P><P>Our results confirm the association signals between SLE and <I>TNIP1</I> variants in multiple populations and provide new insight into the mechanism by which <I>TNIP1</I> variants may contribute to SLE pathogenesis.</P>

A MICROSTRUCTURAL MODEL OF THE THERMAL CONDUCTIVITY OF DISPERSION TYPE FUELS WITH A FUEL MATRIX INTERACTION LAYER

Williams, A.F.,Leitch, B.W.,Wang, N. Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.7

This paper describes a finite element model of the microstructure of dispersion type nuclear fuels, which can be used to determine the effective thermal conductivity of the fuels during irradiation. The model simulates a representative region of the fuel as a prism shaped unit cell made of brick elements. The elements within the unit cell are assigned material properties of either the fuel or the matrix depending on position, in such a way as to represent randomly distributed fuel particles with a size distribution similar to that of the as manufactured fuel. By applying an appropriate heat flux across the unit cell it is possible to determine the effective thermal conductivity of the unit cell as a function of the volume fraction of the fuel particles. The presence of a fuel/matrix interaction layer is simulated by the addition of a third set of material properties that are assigned to the finite elements that surround each fuel particle. In this way the effective thermal conductivity of the material may also be determined as a function of the volume fraction of the interaction layer. Work is on going to add fission gas bubbles in the fuel as a fourth phase to the model.

A new pH sensitive fluorescent and white light emissive material through controlled intermolecular charge transfer

Park, Y. I.,Postupna, O.,Zhugayevych, A.,Shin, H.,Park, Y.-S.,Kim, B.,Yen, H.-J.,Cheruku, P.,Martinez, J. S.,Park, J. W.,Tretiak, S.,Wang, H.-L. Royal Society of Chemistry 2015 Chemical Science Vol.6 No.1

<▼1><P>Fabrication of a unique white light LED from a stimuli-responsive organic molecule is reported. Emission properties are dominated by the pH of the solution through intermolecular charge transfer.</P></▼1><▼2><P>A new, pH dependent and water-soluble, conjugated oligomer (amino, trimethylammonium oligophenylene vinylene, <B>ATAOPV</B>) was synthesized with a quaternary ammonium salt and an aromatic amine at the two ends of a π-conjugated oligomer, thus creating a strong dipole across the molecule. A unique white light LED is successfully fabricated from a stimuli responsive organic molecule whose emission properties are dominated by the pH value of the solution through controlled intermolecular charge transfer.</P></▼2>

A Microstructural Model of the Thermal Conductivity of Dispersion Type Fuels with a Fuel Matrix Interaction Layer

A.F. Williams,B.W. Leitch,N. Wang 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.7

This paper describes a finite element model of the microstructure of dispersion type nuclear fuels, which can be used todetermine the effective thermal conductivity of the fuels during irradiation. The model simulates a representative region of thefuel as a prism shaped unit cell made of brick elements. The elements within the unit cell are assigned material properties ofeither the fuel or the matrix depending on position, in such a way as to represent randomly distributed fuel particles with a sizedistribution similar to that of the as manufactured fuel. By applying an appropriate heat flux across the unit cell it is possible todetermine the effective thermal conductivity of the unit cell as a function of the volume fraction of the fuel particles. Thepresence of a fuel/matrix interaction layer is simulated by the addition of a third set of material properties that are assigned tothe finite elements that surround each fuel particle. In this way the effective thermal conductivity of the material may also bedetermined as a function of the volume fraction of the interaction layer. Work is on going to add fission gas bubbles in the fuelas a fourth phase to the model.

An Analytical Model for Evaluating Axial Boundary Stiffness of Steel Beam Restrained by Neighboring Floor Systems

K. Q. Wang,C. Fang,G. Q. Li,B. A. Izzuddin 한국강구조학회 2011 International Journal of Steel Structures Vol.11 No.4

Extreme loading such as blast and impact usually lead to a disastrous damage on targeted columns, such that the column can be seen as completely removed. Under this circumstance, the ‘double-span’ beam system bridging over the removed column can deflect greatly, and catenary action of the beam plays an important role in enhancing its resistance. In this context, a reliable evaluation of the boundary axial stiffness is crucial in predicting the actual response of axially restrained beams. Although a considerable number of factors affecting the boundary restraints of the beam in a frame have been investigated, the influences of planar stiffness offered by surrounding slabs systems have hardly been addressed. This paper proposes a design-oriented procedure for evaluating the boundary axial stiffness provided by adjacent slab systems. Firstly, three components that contribute to the axial restrain stiffness are identified, namely, slabs, steel beams and studs. Then nonlinear deformation functions of the components are proposed, from which the axial restraining stiffness formulas are derived. Due to the fact that only a part of slab length is attributed to resisting the external force if a sufficient slab length is allowed, an ‘effective length’has to be considered. The axial stiffness formulas are then modified on the basis of the effective length. Subsequently, the reliability of the proposed formulas is validated against a case study of twenty FE examples, and good correlations are observed. Finally, additional stiffness offered by the minor axis bending of the steel beams perpendicular to the restrained beam is investigated, and it is found that the influence is relatively small, and thus can be ignored.

Role of activity in human dynamics

Zhou, T.,Kiet, H. A. T.,Kim, B. J.,Wang, B.-H.,Holme, P. Editions de Physique 2008 Europhysics letters Vol.82 No.2

<P>The human society is a very complex system; still, there are several non-trivial, general features. One type of them is the presence of power-law–distributed quantities in temporal statistics. In this letter, we focus on the origin of power laws in rating of movies. We present a systematic empirical exploration of the time between two consecutive ratings of movies (the <I>interevent time</I>). At an aggregate level, we find a monotonous relation between the activity of individuals and the power law exponent of the interevent time distribution. At an individual level, we observe a heavy-tailed distribution for each user, as well as a negative correlation between the activity and the width of the distribution. We support these findings by a similar data set from mobile phone text-message communication. Our results demonstrate a significant role of the activity of individuals on the society-level patterns of human behavior. We believe this is a common character in the interest-driven human dynamics, corresponding to (but different from) the universality classes of task-driven dynamics.</P>

Variants in hormone-related genes and the risk of biliary tract cancers and stones: a population-based study in China

Park, S. K.,Andreotti, G.,Sakoda, L. C.,Gao, Y.-T.,Rashid, A.,Chen, J.,Chen, B. E.,Rosenberg, P. S.,Shen, M.-C.,Wang, B.-S.,Han, T.-Q.,Zhang, B.-H.,Yeager, M.,Chanock, S.,Hsing, A. W. Oxford University Press 2009 Carcinogenesis Vol.30 No.4

<P>Biliary tract cancers, encompassing gallbladder, extrahepatic bile duct and ampulla of Vater cancers, are uncommon but often fatal malignancies. Hormone-related factors, including parity, oral contraceptive use, obesity, and gallstones, have been implicated in the etiology of these cancers. To further clarify the role of hormones in biliary tract cancers and biliary stones, we genotyped 18 single-nucleotide polymorphisms (SNPs) in nine genes involved in steroid hormone biosynthesis, metabolism and transport in a population-based case-control study in Shanghai, China. This study included subjects who completed an interview and provided blood, which totaled 411 biliary tract cancer and 893 biliary stone patients and 786 healthy Shanghai residents. The CYP1A1 IVS1 + 606 (rs2606345) T allele was associated with gallbladder [odds ratio (OR) = 2.0, 95% confidence interval (CI), 1.3-3.0] and bile duct cancers (OR = 1.8, 95% CI = 1.1-3.1), whereas the CYP1A1 Ex7 + 131 (rs1048943) G allele was associated with ampulla of Vater cancer (OR = 2.9, 95% CI = 1.5-5.4). After taking into account multiple comparisons for SNPs within each gene, CYP1A1 was significantly associated with gallbladder (P = 0.004) and ampulla of Vater cancers (P = 0.01), but borderline with bile duct cancer (P = 0.06). The effect of CYP1A1 IVS1 + 606 on gallbladder cancer was more pronounced among non-obese (body mass index < 23) (OR = 3.3, 95% CI = 1.8-6.1; P interaction = 0.001). Among women taking oral contraceptives, the effect of SHBG Ex8 + 6 (rs6259) on gallbladder cancer (OR = 6.7, 95% CI = 2.2-20.5; P interaction = 0.001) and stones (OR = 2.3, 95% CI = 1.1-4.9; P-interaction = 0.05) was statistically significant. Our findings suggest that common variants in hormone-related genes contribute to the risk of biliary tract cancers and stones, possibly by modulating hormone metabolism.</P>