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991.
Effective algorithm for solving inverse problems – geomechanical application. When working with numerical models, it is essential to determine model parameters which are as realistic as possible. Optimization techniques are being employed more and more frequently for solving this task. However, using these methods may lead to very high time costs – in particular, if rather complicated forward calculations are involved. In this paper, we present a class of methods that allows estimating the solution of this kind of optimization problems based on relatively few sampling points. We put very weak constraints on the sampling point distribution; hence, they may be taken from previous forward calculations as well as from alternative sources. Starting from an introduction into the theoretical approach, a strategy for speeding up inverse optimization problems is introduced which is illustrated by an example geomechanics. 相似文献
992.
α粒子微束定点照射--细胞的放射生物学效应及精确性分析 总被引:2,自引:0,他引:2
进行微束试验的关键是能够精确地控制照射的粒子数和将粒子准确地射入受照射位点.该研究通过对哥伦比亚大学单粒子微束装置在精确性、准确性以及各项指标的分析发现该装置可精确地控制照射粒子数,精确率为98.4%.同时,它可将α粒子准确地射入受照射位点,束半径为34,达到设计4的标准.在对细胞特定位点如细胞质照射上,粒子击中细胞质至少一个位点的概率为90%,在这一过程中的偶然核击中率,对大多数照射剂量(8个粒子)均小于0.8%.应用该微束装置的放射生物学研究发现单个α粒子仅导致大约20%的致死率,其存活率曲线类似于用常规照射获得的平均粒子存活曲线.诱变试验首次证实单个α粒子在AL细胞的CD59基因位点可诱导出比对照高出3倍数量的诱变子,诱变率随粒子数的增加而增加.这一结果不同于常规照射中,诱变率在高剂量照射后下降的结论. 相似文献
993.
v. Pohl R. Trendelenburg Zimmermann E. Brüche S. Nickel Zycha Liese Schulz Graf A. Troche T. Perkitny M. Lüdtke Frey-Wyssling K. Storch Otto Kratky A. v. Wacek Finkbeiner K. Storch Munds Paula Sarten Ernst Tschanter A. Kraus R. Lechner Schaile Thiele W. Küch Kräß Hengerer Kollmann A. Nowak 《Holz als Roh- und Werkstoff》1940,3(4):128-136
Ohne Zusammenfassung 相似文献
994.
R. Trendelenburg Frey-Wyssling O. Kratky Gertraude Körner-Hennig Egner v. Pohl M. Lüdtke K. Storch Klar Zimmermann B. Thunell L. Metz Thiele Kollmann W. Wenhart A. Troche 《Holz als Roh- und Werkstoff》1940,3(6):202-207
Ohne Zusammenfassung 相似文献
995.
R. Trendelenburg Botteri Schulz Zimmermann Schulz Gustav G. Klem Frey-Wyssling O. Kratky A. v. Wacek O. Kratky G. Becker Egner Graf B. Thunell M. Lüdtke S. Nickel A. Kraus Klar Finkbeiner Müller E. Becker Zimmermann v. Pohl Lechner Richard Huber L. Metz Thiele Schlüter Egner W. Wenhart Graf Kinberg Kraemer 《Holz als Roh- und Werkstoff》1940,3(5):165-174
Ohne Zusammenfassung 相似文献
996.
Tom Eeckelaert Raf Schoofs Michiel Steyaert Georges Gielen Willy Sansen 《Analog Integrated Circuits and Signal Processing》2008,55(1):37-45
This paper presents a 3rd-order continuous-time Delta-Sigma modulator with a resolution of 10 bits for a 10 MHz signal bandwidth.
It is designed in a standard 0.18 μm CMOS technology and consumes only 6 mW. After the design/selection of the topologies
for the integrators, comparator and D/A converters, optimal sizing of the complete modulator was ensured by using a hierarchical
bottom-up, multi-objective evolutionary design methodology. With this methodology, a set of Pareto-optimal modulator designs
is generated by using Pareto-optimal performance solutions of the hierarchically decomposed lower-level subblocks. From the
generated Pareto-optimal design set, a final optimal design is chosen that complies with the specifications for the 802.11a/b/g
WLAN standard and has minimal power consumption. 相似文献
997.
Mauricio D. Gutierrez Vasileios Tenentes Daniele Rossi Tom J. Kazmierski 《Journal of Electronic Testing》2017,33(4):463-477
Low power fault tolerance design techniques trade reliability to reduce the area cost and the power overhead of integrated circuits by protecting only a subset of their workload or their most vulnerable parts. However, in the presence of faults not all workloads are equally susceptible to errors. In this paper, we present a low power fault tolerance design technique that selects and protects the most susceptible workload. We propose to rank the workload susceptibility as the likelihood of any error to bypass the logic masking of the circuit and propagate to its outputs. The susceptible workload is protected by a partial Triple Modular Redundancy (TMR) scheme. We evaluate the proposed technique on timing-independent and timing-dependent errors induced by permanent and transient faults. In comparison with unranked selective fault tolerance approach, we demonstrate a) a similar error coverage with a 39.7% average reduction of the area overhead or b) a 86.9% average error coverage improvement for a similar area overhead. For the same area overhead case, we observe an error coverage improvement of 53.1% and 53.5% against permanent stuck-at and transition faults, respectively, and an average error coverage improvement of 151.8% and 89.0% against timing-dependent and timing-independent transient faults, respectively. Compared to TMR, the proposed technique achieves an area and power overhead reduction of 145.8% to 182.0%. 相似文献
998.
Yangyang Li Yakui Weng Xinmao Yin Xiaojiang Yu S. R. Sarath Kumar Nimer Wehbe Haijun Wu Husam N. Alshareef Stephen J. Pennycook Mark B. H. Breese Jingsheng Chen Shuai Dong Tom Wu 《Advanced functional materials》2018,28(7)
Magnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long‐wavelength regimes. In this work, the discovery of orthorhombic‐structured Ti2O3 films is reported as a unique narrow‐bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well‐known corundum‐structured Ti2O3 polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti2O3 thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti2O3 polymorph is found to be n‐type with a very high electron concentration, while the bulk‐type trigonal‐structured Ti2O3 is p‐type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti2O3, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti2O3, which is confirmed by X‐ray magnetic circular dichroism measurements. Using first‐principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti2O3. The room‐temperature ferromagnetism observed in orthorhombic‐structured Ti2O3, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases. 相似文献
999.
A new photodiode for the UV/blue spectral range, which can be integrated monolithically with CMOS circuits, is presented. Such optoelectronic integrated circuits (OEICs) with a high sensitivity in the UV/blue spectral range are needed in near-future optical storage systems like digital versatile disk (DVD) or digital video recording (DVR). At 400 nm, our so-called finger photodiode achieves a responsivity of 0.23 A/W corresponding to a quantum efficiency η of 70% [with an antireflection coating (ARC)] and rise and fall times of 1.0 ns and 1.1 ns, respectively. The finger photodiode can be used in the red spectral range, too. At 638 nm, the responsivity is 0.49 A/W (η=95%) and rise and fall times of less than 2.3 ns are achieved. For the integration of the finger photodiode in an industrial 1 μm twin-well CMOS process, only one additional mask is needed in order to block out the threshold voltage implantation in the photo-active region 相似文献
1000.
Tom Nelson Oder Andrew Smith Mark Freeman Michael Mcmaster Bo Cai Mim Lal Nakarmi 《Journal of Electronic Materials》2014,43(5):1370-1378
The properties of ZnO thin films codoped with lithium and phosphorus have been characterized. The films were deposited from high-purity ZnO and Li3PO4 solid targets onto c-plane sapphire substrates by radiofrequency (RF) magnetron sputtering. A substrate temperature of 900°C was determined as optimum for depositing undoped ZnO films with background electron concentration of 9.9 × 1015 cm?3 as the buffer layer on the sapphire substrate. Postdeposition annealing was carried out using rapid thermal processing in O2 at temperatures ranging from 500°C to 1000°C for 3 min. Analyses performed using low-temperature photoluminescence spectroscopy measurements revealed luminescence peaks at 3.356 eV, 3.307 eV, 3.248 eV, and 3.203 eV at 12 K for the codoped samples. X-ray diffraction 2θ-scans showed a single peak at about 34.4° with full-width at half-maximum of about 0.09°. Hall-effect measurements revealed initial p-type conductivities, but these were unstable and toggled between p-type and n-type over time with Hall concentrations that varied between 2.05 × 1013 cm?3 and 2.89 × 1015 cm?3. The fluctuation in the carrier type could be due to lateral inhomogeneity in the hole concentration caused by stacking faults in the films. An additional cause could be the small Hall voltages in the measurements, which could be significantly impacted by even small spikes in signal noise inherent in the measurements. 相似文献