Biography

Chopra’s research is fundamental and focused on physics of magnetism and magnetic materials; evolution of coupled and uncoupled properties from quantum to semi-classical length scales; high-resolution micromagnetic imaging; phase transitions in multiferroics. Key research strategy to break barriers to observing new phenomena is via development of ultra-high resolution (nano to pico-range) techniques.

Research highlights include discovery of non-Joulian magnets that cracked centuries old edifice of Joule’s paradigm on magnetostriction (Nature 2015); discovery of enhanced elastic properties approaching theoretical values in metals at Fermi length scale (PRB 2011, 2012); first direct proof of conductance quantization in metals (PRB 2010); discovery of surface energy based ‘Hume-Rothery’ rule for alloying at mesoscale (J. Appl. Phys., 2012); oscillatory magnetoresistance in quantum conductors (Nature materials, 2005); first observation of magneto-elastic twins in magnetic shape memory alloys strains (PRB, 2000); refining crystal structure of primary strengthening precipitates in aluminum-based aerospace alloys (found not to be structure of Bergman, Waugh and Pauling, Philosophical Magazine Letters, 1995). Dr. Chopra’s research has been variously highlighted by Nature, Science, Science News, MRS, TMS, APS; Scientific American, NSF, etc.

Research Interests: Non-Joulian magnets; magnetism and magnetic properties; micromagnetics; multiferroics; quantized conductance.

Research Interests

  • Mechanics of (Magnetic) Materials Across Length Scales
  • Magneto-elastic Effects and the Modulus-Defect
  • Non-Destructive Testing of Mechanical Properties of Materials

Courses Taught

Number

Name

Level

ENGR 1117

Engineering Graphics

Undergraduate

ENGR 4201

Micro- to Nano-sized Machines

Undergraduate

MEE 0843

Technology Transformations

Undergraduate

MEE 5203

Advanced Materials Science

Graduate

ENVT 0845

The Environment

Undergraduate

Selected Publications

  • Pacifico, M.S. & Chopra, H.D. (2019). Anomalous magnetic properties of pre-martensitic iron-palladium alloys. Journal of the Physical Society of Japan, 88(1). doi: 10.7566/JPSJ.88.013701

  • Chopra, H.D. (2019). Giant magneto-elastic and magneto-volume effects in Fe–Al. Journal of the Physical Society of Japan, 88(3). doi: 10.7566/JPSJ.88.033702

  • Chopra, H.D., Ravishankar, A., Pacifico, M.S., & Forst, M.L. (2018). Non-Joulian Magnetostriction and Non-Joulian Magnetism. Physica Status Solidi (B) Basic Research, 255(12). doi: 10.1002/pssb.201800214

  • Saurav, T.M., Forst, M.L., Boligitz, J.A., & Chopra, H.D. (2017). Contracting non-Joulian magnets. Physical Review B, 95(17). doi: 10.1103/PhysRevB.95.174425

  • Chopra, H.D. & Wuttig, M. (2016). Addendum: Non-Joulian magnetostriction. Nature, 538(7625), p. 416. England. doi: 10.1038/nature19064

  • Xu, B., Luo, Z., Wilson, A.J., Chen, K.e., Gao, W., Yuan, G., Chopra, H.D., Chen, X., Willets, K.A., Dauter, Z., & Ren, S. (2016). Multifunctional Charge-Transfer Single Crystals through Supramolecular Assembly. Adv Mater, 28(26), pp. 5322-5329. Germany. doi: 10.1002/adma.201600383

  • Chopra, H.D. & Wuttig, M. (2015). Non-Joulian magnetostriction. Nature, 521(7552), pp. 340-343. England. doi: 10.1038/nature14459

  • Chopra, H.D., Armstrong, J.N., & Hua, S.Z. (2013). Metallic bonds become molecular-like in atomic-sized devices. Retrieved from http://arxiv.org/

  • Armstrong, J.N., Hua, S.Z., & Chopra, H.D. (2013). Anisotropic Curie temperature materials. Physica Status Solidi (B) Basic Research, 250(2), pp. 387-395. doi: 10.1002/pssb.201248186

  • Chopra, H.D., Armstrong, J.N., & Hua, S.Z. (2013). Anisotropic curie temperature materials (plenary). TMS Annual Meeting, pp. 177-188. doi: 10.1002/9781118658352.ch20

  • Armstrong, J.N., Gande, E.M., Vinti, J.W., Hua, S.Z., & Chopra, H.D. (2012). Physical properties of a two-component system at the Fermi and Sharvin length scales. Journal of Applied Physics, 112(10). doi: 10.1063/1.4766454

  • Armstrong, J.N., Gande, E.M., Vinti, J.W., Hua, S.Z., & Chopra, H.D. (2012). Emergence of physical properties mapped in a two-component system. Retrieved from http://arxiv.org/

  • Armstrong, J.N., Hua, S.Z., & Chopra, H.D. (2012). Strength of metals at the Fermi length scale. Physica Status Solidi - Rapid Research Letters, 6(3), pp. 99-101. doi: 10.1002/pssr.201105541

  • Armstrong, J.N., Hua, S.Z., & Chopra, H.D. (2011). Stepwise emergence of an intensive physical property from a single-atom
    to bulk.
    Retrieved from http://arxiv.org/

  • Jin, Y.M. & Chopra, H.D. (2011). Altering magnetostrictive strain pathways via morphology of spontaneously aligned domains. Physical Review B - Condensed Matter and Materials Physics, 84(14). doi: 10.1103/PhysRevB.84.140401

  • Armstrong, J.N., Hua, S.Z., & Chopra, H.D. (2011). Cooperative motion of domain walls in magnetic multilayers. Physical Review B - Condensed Matter and Materials Physics, 83(5). doi: 10.1103/PhysRevB.83.054426

  • Armstrong, J.N., Hua, S.Z., & Chopra, H.D. (2011). Mechanics of quantum and Sharvin conductors. Physical Review B - Condensed Matter and Materials Physics, 83(23). doi: 10.1103/PhysRevB.83.235422

  • Armstrong, J.N., Hua, S.Z., & Chopra, H.D. (2011). Stability of quantum and Sharvin constrictions. Retrieved from http://arxiv.org/

  • Armstrong, J.N., Schaub, R.M., Hua, S.Z., & Chopra, H.D. (2010). Channel saturation and conductance quantization in single-atom gold constrictions. Physical Review B - Condensed Matter and Materials Physics, 82(19). doi: 10.1103/PhysRevB.82.195416

  • Bathany, C., Romancer, M.L.e., Armstrong, J.N., & Chopra, H.D. (2010). Morphogenesis of maze-like magnetic domains. Physical Review B - Condensed Matter and Materials Physics, 82(18). doi: 10.1103/PhysRevB.82.184411

  • Armstrong, J.N., Felske, J.D., & Chopra, H.D. (2010). Multiple phase transitions found in a magnetic Heusler alloy and thermodynamics of their magnetic internal energy. Physical Review B - Condensed Matter and Materials Physics, 81(17). doi: 10.1103/PhysRevB.81.174405

  • Armstrong, J.N., Sullivan, M.R., & Chopra, H.D. (2009). Antiferromagnetic spin and twin domain walls govern hysteretic expressions of exchange anisotropy. Physical Review B - Condensed Matter and Materials Physics, 80(10). doi: 10.1103/PhysRevB.80.104429

  • Huntington, M.D., Armstrong, J.N., Sullivan, M.R., Hua, S.Z., & Chopra, H.D. (2008). Mechanistic understanding of transition between quantized conductance plateaus under strain perturbation. Physical Review B - Condensed Matter and Materials Physics, 78(3). doi: 10.1103/PhysRevB.78.035442

  • Armstrong, J.N., Sullivan, M.R., Romancer, M.L.e., Chernenko, V.A., & Chopra, H.D. (2008). Role of magnetostatic interactions in micromagnetic structure of multiferroics. Journal of Applied Physics, 103(2). doi: 10.1063/1.2817640

  • Li, X.L., Hua, S.Z., Chopra, H.D., & Tao, N.J. (2006). Formation of atomic point contacts and molecular junctions with a combined mechanical break junction and electrodeposition method. MICRO & NANO LETTERS, 1(2), pp. 83-88. doi: 10.1049/mnl:20065049

  • Heil, T.M., Reynolds, W.T., Willard, M.A., Sullivan, M.R., Huntington, M.D., & Chopra, H.D. (2005). Effects of annealing on the martensite and magnetic transformations in A Ni-Fe-Ga ferromagnetic shape memory alloy. Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005, 2, pp. 221-226.

  • Chopra, H.D., Sullivan, M.R., Ludwig, A., & Quandt, E. (2005). Magnetoelastic and magnetostatic interactions in exchange-spring multilayers. Physical Review B - Condensed Matter and Materials Physics, 72(5). doi: 10.1103/PhysRevB.72.054415

  • Sullivan, M.R., Pirotta, S.J., Chernenko, V.A., Wu, G.H., Balasubramanium, G., Hua, S.Z., & Chopra, H.D. (2005). Magnetic mosaics in crystalline tiles: The novel concept of polymagnets (invited). International Journal of Applied Electromagnetics and Mechanics, 22(1-2), pp. 11-23. doi: 10.3233/jae-2005-688

  • Sullivan, M.R., Boehm, D.A., Ateya, D.A., Hua, S.Z., & Chopra, H.D. (2005). Ballistic magnetoresistance in nickel single-atom conductors without magnetostriction. Physical Review B - Condensed Matter and Materials Physics, 71(2). doi: 10.1103/PhysRevB.71.024412

  • Chopra, H.D., Sullivan, M.R., Armstrong, J.N., & Hua, S.Z. (2005). The quantum spin-valve in cobalt atomic point contacts. Nature Materials, 4(11), pp. 832-837. doi: 10.1038/nmat1510

  • Chopra, H.D. & Sullivan, M.R. (2005). Method to study temperature and stress induced magnetic transitions. REVIEW of SCIENTIFIC INSTRUMENTS, 76(1). doi: 10.1063/1.1832448

  • Sullivan, M.R., Ateya, D.A., Pirotta, S.J., Shah, A.A., Wu, G.H., & Chopra, H.D. (2004). In situ study of temperature dependent magnetothermoelastic correlated behavior in ferromagnetic shape memory alloys. Journal of Applied Physics, 95(11 II), pp. 6951-6953. doi: 10.1063/1.1690197

  • Hua, S.Z. & Chopra, H.D. (2004). Quantum probe for molecular synthesis at room temperature. Retrieved from http://arxiv.org/

  • Sullivan, M.R. & Chopra, H.D. (2004). Temperature- and field-dependent evolution of micromagnetic structure in ferromagnetic shape-memory alloys. Physical Review B - Condensed Matter and Materials Physics, 70(9). doi: 10.1103/PhysRevB.70.094427

  • Sullivan, M.R., Shah, A.A., & Chopra, H.D. (2004). Pathways of structural and magnetic transition in ferromagnetic shape-memory alloys. Physical Review B - Condensed Matter and Materials Physics, 70(9). doi: 10.1103/PhysRevB.70.094428

  • Yang, D.X., Repetski, E.J., Chopra, H.D., Chen, P.J., & Egelhoff, W.F. (2003). Highly deleterious role of small amounts of carbon on the giant magnetoresistance effect. Journal of Applied Physics, 93(10 3), pp. 8415-8417. doi: 10.1063/1.1558100

  • Hua, S.Z. & Chopra, H.D. (2003). 100,000 % ballistic magnetoresistance in stable Ni nanocontacts at room temperature. Physical Review B - Condensed Matter and Materials Physics, 67(6). doi: 10.1103/PhysRevB.67.060401

  • Sullivan, M.R., Ateya, D.A., Pirotta, S., Shah, A.A., Wu, G.H., & Chopra, H.D. (2003). Fundamental investigation of ferromagnetic shape memory alloys: A new perspective. Materials Research Society Symposium - Proceedings, 785, pp. 457-467. doi: 10.1557/proc-785-d13.2

  • Hua, S.Z., Sachs, F., Yang, D.X., & Chopra, H.D. (2002). Microfluidic actuation using electrochemically generated bubbles. Anal Chem, 74(24), pp. 6392-6396. United States. doi: 10.1021/ac0259818

  • Siu, I.L., Egelhoff, W.F., Yang, D.X., & Chopra, H.D. (2002). Magnetization reversal in half-metallic epitaxial CrO 2 films. Journal of Applied Physics, 92(9), pp. 5409-5412. doi: 10.1063/1.1510568

  • Yang, D.X., Chopra, H.D., Shashishekar, B., Chen, P.J., & Egelhoff, W.F. (2002). Carbon: A bane for giant magnetoresistance magnetic multilayers. Applied Physics Letters, 80(16), pp. 2943-2945. doi: 10.1063/1.1469682

  • Repetski, E.J., Yang, D.X., Chopra, H.D., Chen, P.J., & Egelhoff, W.F. (2002). Improved interfaces and magnetic properties in spin valves using Ni80Fe20 seed layer. Journal of Applied Physics, 91(6), pp. 3891-3895. doi: 10.1063/1.1448892

  • Chopra, H.D., Yang, D.X., Chen, P.J., & Egelhoff, W.F. (2002). Surfactant-assisted atomic-level engineering of spin valves. Physical Review B - Condensed Matter and Materials Physics, 65(9), pp. 1-7. doi: 10.1103/PhysRevB.65.094433

  • Chopra, H.D. & Hua, S.Z. (2002). Ballistic magnetoresistance over 3000% in Ni nanocontacts at room temperature. Physical Review B - Condensed Matter and Materials Physics, 66(2), pp. 1-3. doi: 10.1103/PhysRevB.66.020403

  • Hua, S.Z., Sachs, F., & Chopra, H.D. (2002). Electrochemically actuated microvalves for microfluidic systems. ASME International Mechanical Engineering Congress and Exposition, Proceedings, pp. 507-512. doi: 10.1115/IMECE2002-39387

  • Wetherhold, R.C. & Chopra, H.D. (2001). Beam model for calculating magnetostriction strains in thin films and multilayers. Applied Physics Letters, 79(23), pp. 3818-3820. doi: 10.1063/1.1421224

  • Chopra, H.D., Hicho, G.E., & Swartzendruber, L.J. (2001). Review of the Jumpsum Based Nondestructive Testing Method for Evaluating Mechanical Properties of Ferromagnetic Materials. Materials Evaluation, 59(10), pp. 1215-1222.

  • Yang, D.X., Kankolenski, K.P., Hua, S.Z., Swartzendruber, L.J., Hicho, G.E., & Chopra, H.D. (2001). Evaluation of mechanical properties of magnetic materials using a non-destructive method. IEEE Transactions on Magnetics, 37(4 I), pp. 2758-2760. doi: 10.1109/20.951298

  • Yang, D.X., Shashishekar, B., Chopra, H.D., Chen, P.J., & Egelhoff, W.F. (2001). Atomic engineering of spin valves using Ag as a surfactant. Journal of Applied Physics, 89(11 II), pp. 7121-7123. doi: 10.1063/1.1359225

  • Kankolenski, K.P., Hua, S.Z., Yang, D.X., Hicho, G.E., Swartzendruber, L.J., Zang, Z., & Chopra, H.D. (2000). Non-destructive evaluation of mechanical properties of magnetic materials. Materials Research Society Symposium - Proceedings, 591, pp. 157-162.

  • Chopra, H.D., Repetski, E.J., Brown, H.J., Chen, P.J., Swartzendruber, L.J., & Egelhoff, W.F. (2000). Magnetic behavior of atomically engineered NiO-Co-Cu-based giant magnetoresistance spin valves using Pb as a surface modifier. Acta Materialia, 48(13), pp. 3501-3508. doi: 10.1016/S1359-6454(00)00146-4

  • Yang, D.X., Chopra, H.D., Chen, P.J., Brown, H.J., Swartzendruber, L.J., & Egelhoff, W.F. (2000). Magnetization reversal in polycrystalline NiO-Co exchange anisotropy coupled bilayers. JOURNAL of APPLIED PHYSICS, 87(9), pp. 4942-4944. doi: 10.1063/1.373416

  • Chopra, H.D., Yang, D.X., Chen, P.J., & Egelhoff, W.F. (2000). Contributions to switching field in NiO-Co-Cu-based spin valves. JOURNAL of APPLIED PHYSICS, 87(9), pp. 6986-6988. doi: 10.1063/1.373426

  • Yang, D.X., Chopra, H.D., Chen, P.J., Brown, H.J., Swartzendruber, L.J., & Egelhoff, W.F. (2000). Magnetization reversal in polycrystalline NiO–Co exchange anisotropy coupled bilayers. Journal of Applied Physics, 87(9), pp. 4942-4944. doi: 10.1063/1.373416

  • Chopra, H.D., Yang, D.X., Chen, P.J., & Egelhoff, W.F. (2000). Contributions to switching field in NiO-Co-Cu-based spin valves. Journal of Applied Physics, 87(9 III), pp. 6986-6988. doi: 10.1063/1.373426

  • Chopra, H.D., Yang, D.X., Chen, P., Brown, H., Swartzendruber, L., & Egelhoff, W. (2000). Nature of magnetization reversal in exchange-coupled polycrystalline NiO-Co bilayers. Physical Review B - Condensed Matter and Materials Physics, 61(22), pp. 15312-15320. doi: 10.1103/PhysRevB.61.15312

  • Chopra, H.D., Yang, D.X., Chen, P., Parks, D., & Egelhoff, W. (2000). Nature of coupling and origin of coercivity in giant magnetoresistance NiO-Co-Cu-based spin valves. Physical Review B - Condensed Matter and Materials Physics, 61(14), pp. 9642-9652. doi: 10.1103/PhysRevB.61.9642

  • Chopra, H.D., Ji, C., & Kokorin, V. (2000). Magnetic-field-induced twin boundary motion in magnetic shape-memory alloys. Physical Review B - Condensed Matter and Materials Physics, 61(22), pp. R14913-R14915. doi: 10.1103/PhysRevB.61.R14913

  • Chopra, H.D., Yang, D.X., & Wilson, P. (2000). Magnetoelastic dependence of switching field in TbFe-FeCo giant magnetostrictive spring-magnet multilayers. Journal of Applied Physics, 87(9 II), pp. 5780-5782. doi: 10.1063/1.372520

  • Chopra, H.D., Ludwig, A., Quandt, E., Hua, S.Z., Brown, H.J., Swartzendruber, L.J., & Wuttig, M. (1999). Magnetic mesostructure of giant magnetostrictive spring magnet type multilayers. JOURNAL of APPLIED PHYSICS, 85(8), pp. 6238-6240. doi: 10.1063/1.370232

  • Chopra, H.D., Ludwig, A., Quandt, E., Hua, S.Z., Brown, H.J., Swartzendruber, L.J., & Wuttig, M. (1999). Magnetic mesostructure of giant magnetostrictive spring magnet type multilayers. Journal of Applied Physics, 85(8 II B), pp. 6238-6240. doi: 10.1063/1.370232

  • Chopra, H.D. & Wuttig, M. (1999). Deformation by twin boundary rotation. ADVANCES in TWINNING, pp. 267-278. Retrieved from http://gateway.webofknowledge.com/

  • Edelstein, A.S., Bussmann, K.M., Turner, D.C., & Chopra, H.D. (1998). Interlayer coupling in Co/Cu/permalloy/Cu multilayers. Journal of Applied Physics, 83(9), pp. 4848-4854. doi: 10.1063/1.367282

  • Hua, S.Z., Lashmore, D.S., Swartzendruber, L.J., Egelhoff, W.F., Raj, K., & Chopra, H.D. (1997). Observation of domain dynamics in giant magnetoresistive Co-Cu-based polycrystalline multilayers. JOURNAL of APPLIED PHYSICS, 81(8), pp. 4582-4584. doi: 10.1063/1.364749

  • Chopra, H.D., Hockey, B.J., Chen, P.J., McMichael, R.D., & Egelhoff, W.F. (1997). Nanostructuue, interfaces, and magnetic properties in giant magnetoresistive NiO-Co-Cu-based spin valves. JOURNAL of APPLIED PHYSICS, 81(8), pp. 4017-4019. doi: 10.1063/1.365273

  • Swartzendruber, L.J., Hicho, G.E., Chopra, H.D., Leigh, S.D., Adam, G., & Tsory, E. (1997). Effect of plastic strain on magnetic and mechanical properties of ultralow carbon sheet steel. Journal of Applied Physics, 81(8 PART 2A), pp. 4263-4265. doi: 10.1063/1.364796

  • Chopra, H.D., Hockey, B.J., Chen, P.J., McMichael, R.D., & Egelhoff, W.F. (1997). Nanostructure, interfaces, and magnetic properties in giant magnetoresistive NiO-Co-Cu-based spin valves. Journal of Applied Physics, 81(8 PART 2A), pp. 4017-4019. doi: 10.1063/1.365273

  • Hua, S.Z., Lashmore, D.S., Swartzendruber, L.J., Egelhoff, W.F., Raj, K., & Chopra, H.D. (1997). Observation of domain dynamics in giant magnetoresistive Co-Cu-based polycrystalline multilayers. Journal of Applied Physics, 81(8 PART 2A), pp. 4582-4584. doi: 10.1063/1.364749

  • Chopra, H.D., Hockey, B.J., Swartzendruber, L.J., Hua, S.Z., Chen, P.J., Raj, K., Lashmore, D.S., Wuttig, M., & Egelhoff, W.F. (1997). Giant magnetoresistance in symmetric spin-valves: nanostructure and domain dynamics. Nanostructured Materials, 9(1-8), pp. 451-454. doi: 10.1016/s0965-9773(97)00098-6

  • Chopra, H.D., Hockey, B., Chen, P., & Egelhoff, W.F. (1997). Nanostructural considerations in giant magnetoresistive Co-Cu-based symmetric spin valves. Physical Review B - Condensed Matter and Materials Physics, 55(13), pp. 8390-8397. doi: 10.1103/PhysRevB.55.8390

  • Chopra, H.D., Bailly, C., & Wuttig, M. (1996). Domain structures in bent In-22.5 at.%Tl polydomain crystals. ACTA MATERIALIA, 44(2), pp. 747-751. Retrieved from http://gateway.webofknowledge.com/

  • Chopra, H.D., Muddle, B.C., & Polmear, I.J. (1996). The structure of primary strengthening precipitates in an Al-1.5wt% Au-4.0wt% Mg-0.5wt% Ag alloy. Philosophical Magazine Letters, 73(6), pp. 351-358. doi: 10.1080/095008396180623

  • Chopra, H.D., Roytburd, A.L., & Wuttig, M. (1996). Temperature-dependent deformation of polydomain phases in an ln-22.5 At. Pct Tl shape memory alloy. Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 27(6), pp. 1695-1700. doi: 10.1007/BF02649827

  • Chopra, H.D. & Wuttig, M. (1995). Precursor shear elastic pseudo-isotropy in near second order martensitic phase transitions. JOURNAL DE PHYSIQUE IV, 5(C8), pp. 157-160. doi: 10.1051/jp4:1995819

  • Nazareth, A.S., Chopra, H.D., Sood, D.K., & Zmood, R.B. (1995). Structure-property relationship of ion-beam sputtered Nd-Fe-B magnetic thin films on (111) silicon. Materials Research Society Symposium - Proceedings, 354, pp. 511-516.

  • Chopra, H.D. & Wuttig, M. (1995). In-situ observation of preparatory untwinning in reverse martensitic transition in an In-22.5at%Tl shape memory alloy. Scripta Metallurgica Et Materiala, 33(4), pp. 521-525. doi: 10.1016/0956-716X(95)00236-O

  • Chopra, H.D., Liu, L.J., Muddle, B.C., & Polmear, I.J. (1995). The structure of metastable 111, precipitates in an Al-2.5 wt0025 Cu-1.5 wt0025 Mg-0.5 wt0025 Ag alloy. Philosophical Magazine Letters, 71(6), pp. 319-324. doi: 10.1080/09500839508241014

  • LI, J., CHOPRA, H.D., & WUTTIG, M. (1994). PREMARTENSITIC ELASTIC SHEAR ANISOTROPY IN FCC ALLOYS. ADVANCED MATERIALS '93, V - a & B, 18(A & B), pp. 821-825. Retrieved from http://gateway.webofknowledge.com/

  • Chopra, H., Gupta, A.K., & Keating, E.L. (1993). Effect of fuel composition and temperature on the pyrolysis of surrogate solid waste. American Society of Mechanical Engineers, Petroleum Division (Publication) PD, 50, pp. 101-106.

  • Chopra, H., Gupta, A.K., Keating, E.L., & White, E.B. (1992). Thermal destruction of solid wastes. SAE Technical Papers. doi: 10.4271/929224

  • Chopra, H., Gupta, A.K., Keating, E.L., & White, E.B. (1992). Thermal destruction of solid wastes. Proceedings of the Intersociety Energy Conversion Engineering Conference, 1.