Электромагнитные процессы в многофазном мостовом инверторе напряжения

Рассмотрены электромагнитные процессы в многофазном, мостовом инверторе напряжения при использовании коммутационных; функций и теории линейных импульсных схем. Для активно-индуктивной нагрузки проанализировано регулирование выходного напряжения широтно-импульсной модуляцией по синусоидальному и прямоугольному законам. До определенного соотношения несущей и выходной частот из условия обмена реактивной энергии нагрузки и коэффициента гармоник по току предпочтительна прямоугольная модуляция. Делается вывод о целесообразности создания схем инверторов с нечетным количеством фаз и соединении нагрузки в звезду. При анализе квазиустановившихся процессов в. системе инвертор-двигатель многофазный асинхронный короткозамкнутый двигатель приводится к эквивалентной двухфазной машине и все необходимые соотношения определяются методом обобщенных векторов. До определенного соотношения несущей и выходной частот также выводятся преимущества прямоугольной модуляции по величине пульсации, момента и скорости

Isolated Eigenvalues of the Ferromagnetic Spin-J XXZ Chain with Kink Boundary Conditions

We investigate the low-lying excited states of the spin J ferromagnetic XXZ chain with Ising anisotropy Delta and kink boundary conditions. Since the third component of the total magnetization, M, is conserved, it is meaningful to study the spectrum for each fixed value of M. We prove that for J>= 3/2 the lowest excited eigenvalues are separated by a gap from the rest of the spectrum, uniformly in the length of the chain. In the thermodynamic limit, this means that there are a positive number of excitations above the ground state and below the essential spectrum

Implementing Quantum Gates using the Ferromagnetic Spin-J XXZ Chain with Kink Boundary Conditions

We demonstrate an implementation scheme for constructing quantum gates using unitary evolutions of the one-dimensional spin-J ferromagnetic XXZ chain. We present numerical results based on simulations of the chain using the time-dependent DMRG method and techniques from optimal control theory. Using only a few control parameters, we find that it is possible to implement one- and two-qubit gates on a system of spin-3/2 XXZ chains, such as Not, Hadamard, Pi-8, Phase, and C-Not, with fidelity levels exceeding 99%.Comment: Updated Acknowledgement

Transport of interface states in the Heisenberg chain

We demonstrate the transport of interface states in the one-dimensional ferromagnetic Heisenberg model by a time dependent magnetic field. Our analysis is based on the standard Adiabatic Theorem. This is supplemented by a numerical analysis via the recently developed time dependent DMRG method, where we calculate the adiabatic constant as a function of the strength of the magnetic field and the anisotropy of the interaction.Comment: minor revision, final version; 13 pages, 4 figure

SWITCH : A randomised, sequential, open-label study to evaluate the efficacy and safety of Sorafenib-sunitinib versus Sunitinib-sorafenib in the treatment of metastatic renal cell cancer

Background Understanding how to sequence targeted therapies for metastatic renal cell carcinoma (mRCC) is important for maximisation of clinical benefit. Objectives To prospectively evaluate sequential use of the multikinase inhibitors sorafenib followed by sunitinib (So-Su) versus sunitinib followed by sorafenib (Su-So) in patients with mRCC. Design, setting, and participants The multicentre, randomised, open-label, phase 3 SWITCH study assessed So-Su versus Su-So in patients with mRCC without prior systemic therapy, and stratified by Memorial Sloan Kettering Cancer Center risk score (favourable or intermediate). Intervention Patients were randomised to sorafenib 400 mg twice daily followed, on progression or intolerable toxicity, by sunitinib 50 mg once daily (4 wk on, 2 wk off) (So-Su), or vice versa (Su-So). Outcome measurements and statistical analysis The primary endpoint was improvement in progression-free survival (PFS) with So-Su versus Su-So, assessed from randomisation to progression or death during second-line therapy. Secondary endpoints included overall survival (OS) and safety. Results and limitations In total, 365 patients were randomised (So-Su, n = 182; Su-So, n = 183). There was no significant difference in total PFS between So-Su and Su-So (median 12.5 vs 14.9 mo; hazard ratio [HR] 1.01; 90% confidence interval [CI] 0.81–1.27; p = 0.5 for superiority). OS was similar for So-Su and Su-So (median 31.5 and 30.2 mo; HR 1.00, 90% CI 0.77–1.30; p = 0.5 for superiority). More So-Su patients than Su-So patients reached protocol-defined second-line therapy (57% vs 42%). Overall, adverse event rates were generally similar between the treatment arms. The most frequent any-grade treatment-emergent first-line adverse events were diarrhoea (54%) and hand-foot skin reaction (39%) for sorafenib; and diarrhoea (40%) and fatigue (40%) for sunitinib. Conclusions Total PFS was not superior with So-Su versus Su-So. These results demonstrate that sorafenib followed by sunitinib and vice versa provide similar clinical benefit in mRCC