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Arima, N.,Kim, S.,Kojima, M. Springer Science + Business Media 2016 Journal of optimization theory and applications Vol.168 No.3
<P>We propose the moment cone relaxation for a class of polynomial optimization problems to extend the results on the completely positive cone programming relaxation for the quadratic optimization model by Arima, Kim and Kojima. The moment cone relaxation is constructed to take advantage of sparsity of the polynomial optimization problems, so that efficient numerical methods can be developed in the future. We establish the equivalence between the optimal value of the polynomial optimization problem and that of the moment cone relaxation under conditions similar to the ones assumed in the quadratic optimization model.</P>
Kojima Tsukasa,Yamasaki Yuzo,Kamitani Takeshi,Yabuuchi Hidetake,Shirasaka Takashi,Shimomiya Yamato,Kondo Masatoshi,Hamasaki Hiroshi,Kato Toyoyuki,Nagao Michinobu,Honda Hiroshi 아시아심장혈관영상의학회 2019 Cardiovascular Imaging Asia Vol.3 No.1
Objective: The smallest diagnostically sufficient amount of contrast media (CM) should be used for coronary computed tomography angiography (CCTA) to minimize the risk of contrast- induced nephrotoxicity in elderly patients with coronary artery disease. The purpose of this study was to propose dynamic-CCTA using a low dose of CM and temporal maximum intensity projection (TMIP) and to investigate its image quality compared to standard-CCTA. Materials and Methods: Participants comprised 30 patients with coronary artery disease who underwent dynamic-CCTA and standard-CCTA using 320-row CT. Dynamic-CCTA was continuously performed at mid-diastole throughout 15–25 cardiac cycles after bolus injection of CM [103 mg iodine/kg body weight (mgI/kg)]. TMIP-CCTA was reconstructed from three-phase dynamic-CCTA data, including a phase with peak enhancement of the ascending aorta. Standard-CCTA was performed using a standard CM dose (259 mgI/kg). Image quality of both TMIP-CCTA and standard-CCTA was analyzed. Results: The amount of CM used in TMIP-CCTA and standard-CCTA was 16.2±2.6 mL and 40.1±7.3 mL, respectively. The mean effective radiation dose was not significantly different between the two methods. Mean coronary attenuation was significantly lower for TMIP-CCTA than standard-CCTA [346.9±82.8 Hounsfield units (HU) vs. 455.4±75.3 HU, p<0.05]. Image noise was significantly lower for TMIP-CCTA than standard-CCTA (20.0±3.2 HU vs. 28.1± 3.6 HU, p<0.05). There were no differences in signal-to-noise ratio and visual assessment scores between the two methods. Conclusion: TMIP-CCTA can be performed using more than 50% less CM with the same image quality as standard-CCTA.
OS Functions for a Distributed FPGA Cluster System
KOJIMA Akira,TOKUNAGA Kazuya,HIRONAKA Tetsuo 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
In reconfigurable computer systems that have reconfigurable resources like FPGA, CPLD etc., OS functions will be necessary to improve utilization of the systems. We have been studying OS functions for these reconfigurable systems. Our first target hardware was tightly coupled FPGA cluster using shared bus and it is easy to access reconfigurable resources, but it is difficult to increase the number of resources. Our second target system is distributed FPGA cluster that is connected by network and it is easy to increase the number of reconfigurable resources, but complicated network handling is necessary to communicate between host computer and reconfigurable resources. In this paper, OS functions for the distributed FPGA cluster system are described, which provide communication services and have compatible simple programming interface with the first target hardware.
Kojima, S.,Ko, J.H. Elsevier 2011 CURRENT APPLIED PHYSICS Vol.11 No.3
The colossal piezoelectric effect of relaxor-based ferroelectrics has attracted much attention due to the technological importance of the conversion between electric and mechanical energies. The mechanism of the significant field effect on piezoelectric properties in this disordered system has become one of the current topics in pure and applied physics. The important key factor in the understanding of relaxors is polar nanoregions (PNRs) which appear at temperatures far above the dielectric maximum or Curie temperature. PNRs play a dominant role in the formation of unique characteristics of relaxors and are regarded to be caused by spatial and dynamic heterogeneity. However, a detailed microscopic picture of their evolution depending on temperature or electric field is still the subject of controversy. The elastic and dynamical properties of the Pb(B<SUB>1/3</SUB>B'<SUB>2/3</SUB>)O<SUB>3</SUB>-type relaxor-based ferroelectrics and their solid solutions with pure ferroelectrics have recently been studied extensively by the broadband micro-Brillouin scattering spectroscopy (BMBS) to clarify the role of PNRs. This paper reviews the recent progress in the understanding of fast dynamics of PNRs of typical relaxor-based ferroelectrics of (1-x)Pb(Mg<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB>-xPbTiO<SUB>3</SUB> and (1-x)Pb(Zn<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB>-xPbTiO<SUB>3</SUB> in the gigahertz frequency range achieved by using BMBS.
Kojima, Takahiko,Nakayama, Kazuya,Ikemura, Kenichiro,Ogura, Takashi,Fukuzumi, Shunichi American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.30
<P>A coordinatively saturated ruthenium(II) complex having tetradentate tris(2-pyridylmethyl)amine (TPA) and bidentate 2,2′-bipyridine (bpy), [Ru(TPA)(bpy)]<SUP>2+</SUP> (<B>1</B>), was oxidized by a Ce(IV) ion in H<SUB>2</SUB>O to afford a Ru(IV)-oxo complex, [Ru(O)(H<SUP>+</SUP>TPA)(bpy)]<SUP>3+</SUP> (<B>2</B>). The crystal structure of the Ru(IV)-oxo complex <B>2</B> was determined by X-ray crystallography. In <B>2</B>, the TPA ligand partially dissociates to be in a facial tridentate fashion and the uncoordinated pyridine moiety is protonated. The spin state of <B>2</B>, which showed paramagnetically shifted NMR signals in the range of 60 to −20 ppm, was determined to be an intermediate spin (<I>S</I> = 1) by the Evans’ method with <SUP>1</SUP>H NMR spectroscopy in acetone-<I>d</I><SUB>6</SUB>. The reaction of <B>2</B> with various oraganic substrates in acetonitrile at room temperature afforded oxidized and oxygenated products and a solvent-bound complex, [Ru(H<SUP>+</SUP>TPA)(bpy)(CH<SUB>3</SUB>CN)], which is intact in the presence of alcohols. The oxygenation reaction of saturated C–H bonds with <B>2</B> proceeds by two-step processes: the hydrogen abstraction with <B>2</B>, followed by the dissociation of the alcohol products from the oxygen-rebound complexes, Ru(III)-alkoxo complexes, which were successfully detected by ESI-MS spectrometry. The kinetic isotope effects in the first step for the reaction of dihydroanthrathene (DHA) and cumene with <B>2</B> were determined to be 49 and 12, respectively. The second-order rate constants of C–H oxygenation in the first step exhibited a linear correlation with bond dissociation energies of the C–H bond cleavage.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-30/ja2037645/production/images/medium/ja-2011-037645_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja2037645'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja2037645'>ACS Electronic Supporting Info</A></P>