Spin-filtered and Spatially Distinguishable Crossed Andreev Reflection in a Silicene-Superconductor Junction

We theoretically investigate the quantum transports in a junction between a superconductor and a silicene nanoribbon, under the effect of a magnetic exchange field. We find that for a narrow nanoribbon of silicene, remarkable crossed Andreev reflection (with a fraction $>50\%$) can be induced in the energy window of the elastic cotunneling, by destroying some symmetries of the system. Since the energy responses of electrons to the exchange field are opposite for opposite spins, these transport channels can be well spin polarized. Moreover, due to the helicity conservation of the topological edge states, these three transport channels are spatially separated in three different locations of the device, making them experimentally distinguishable. This crossed Andreev reflection is a nonlocal quantum interference between opposite edges through evanescent modes. If two superconducting leads with different phases are connected to two edges of the silicene nanoribbon, the crossed Andreev reflection can present Josephson type oscillations, with a maximal fraction $\sim 100\%$.Comment: 8 pages, 7 figure

Fault-Tolerant Control for Systems with Unmatched Actuator Faults and Disturbances

A fault-tolerant control (FTC) scheme for a class of nonlinear systems with unmatched actuator redundancy and unmatched disturbances is proposed in this note. A methodology to construct unified smooth sliding mode control laws and update laws is proposed such that the equivalent injections of the first-order time derivatives of the unmatched actuator faults and unmatched disturbances can appear in the unmatched channels. The unmatched actuator faults and unmatched disturbances are completely canceled by these equivalent injections. Based on this methodology and using the backstepping design procedure, a set of smooth FTC sliding surfaces, FTC laws and update laws are then designed. With the help of the FTC law selecting mechanism, the output tracking errors of the closed-loop FTC system converge to zero asymptotically, and time-varying faults and disturbances are reconstructed. A simulation example is presented to illustrate the effectiveness of the proposed FTC method

Measuring Access to Medicines: A Survey of Prices, Availability and Affordability in Shaanxi Province of China

Objective: To measure the prices and availability of selected medicines in Shaanxi Province after the implementation of new healthcare reform in 2009. Methods: Data on the prices and availability of 47 medicines were collected from 50 public and 36 private sector medicine outlets in six regions of Shaanxi Province, Western China using a standardized methodology developed by the World Health Organization and Health Action International from September to October 2010. Medicine prices were compared with international reference prices to obtain a median price ratio. Affordability was measured as the number of days’ wages required for the lowest-paid unskilled government worker to purchase standard treatments for common conditions. Findings: The mean availabilities of originator brands and lowest-priced generics were 8.9% and 26.5% in the public sector, and 18.1% and 43.6% in the private sector, respectively. The public sector procured generics and originator brands at median price ratios of 0.75 and 8.49, respectively, while patients paid 0.97 and 10.16. Final patient prices for lowest-priced generics and originator brands in the private sector were about 1.53 and 8.36 times their international retail prices, respectively. Public sector vendors applied high markups of 30.4% to generics, and 19.6% to originator brands. In the private sector, originator brands cost 390.7% more, on average, than their generic equivalents. Generic medicines were priced 17.3% higher in the private sector than the public sector. The lowest-paid government worker would need 0.1 day’s wages to purchase captopril for lowest-priced generics from private sector, while 6.6 days’ wages for losartan. For originator brands, the costs rise to 1.2 days’ wages for salbutamol inhaler and 15.6 days’ wages for omeprazole. Conclusions: The prices, availability and affordability of medicines in China should be improved to ensure equitable access to basic medical treatments, especially for the poor. This requires multi-faceted interventions, as well as the review and refocusing of policies, regulations and educational interventions

Incipient Sensor Fault Detection for Inverter Devices in Electric Railway Traction Systems

This paper proposes an incipient sensor fault detection method for three-phase PWM inverter devices in electric railway traction systems. An adaptive and sliding mode unknown input observer is designed for sensor faulty inverter system. The invariant ellipsoid is used to generate threshold. The parameters of the observer are particularly designed such that the estimation errors converge to the threshold invariant ellipsoid before the sensor fault develops to incipient fault degree, and the estimation errors exceed the threshold after the sensor fault develops to incipient fault degree. Finally, simulations based on the traction system in CRH2 (China Railway High-speed) are presented to verify the effectiveness of the proposed method

Interval Sliding Mode Observer based Fault Accommodation for Non-minimum Phase LPV Systems with Online Control Allocation

This paper proposes an interval sliding mode observer (ISMO) based sliding mode actuator fault accommodation (FA) framework for non-minimum phase linear-parameter-varying (LPV) systems involving online control allocation (CA) problem. Firstly, a specifically designed coordinate transformation is introduced to deal with the non-minimum phase issue. Then, for the transformed system, an ISMO is proposed to estimate the set of admissible values for the states of the faulty LPV systems. It is constructed based on the designed interval bounds for the scheduling-parameter-related uncertainties and fault-related items. The observer is designed by combining the interval observer and the sliding mode observer techniques. A fault-tolerant control (FTC) law with an online CA scheme is subsequently designed by stabilizing the proposed ISMO instead of the original faulty LPV system, which guarantees that the unmeasurable states of the original LPV system converge to zero asymptotically, the measurable outputs converge to zero in finite time, and further, the actual control efforts are allocated to all actuators optimally and satisfy prescribed performance. Finally, a simulation based on the inverter used in China Railway High-speed (CRH) is presented to illustrate the effectiveness of the proposed framework

Incipient Voltage Sensor Fault Isolation for Rectifier in Railway Electrical Traction Systems

This paper proposes a dc voltage incipient sensor fault isolation method for single-phase three-level rectifier devices in high-speed railway electrical traction systems. Different incipient fault modes characterizing locations and incipient fault types are parameterized nonlinearly by unknown fault parameters. A new incipient fault isolation method is developed by combining sliding mode technique with nonlinear parametrization adaptive estimation technique. A bank of particular adaptive sliding mode estimators is proposed, which facilitates to derive new isolation residuals and adaptive threshold intervals. The isolability is studied, and the isolable sufficient condition is derived using new functions. For the practical electrical traction system in CRH2 (China Railway High-Speed 2), simulation and experiment based on TDCS-FIB (a software) are presented to verify the effectiveness and feasibility of the proposed method

Access to Paediatric Essential Medicines: A Survey of Prices, Availability, Affordability and Price Components in Shaanxi Province, China

Objective: To evaluate the prices and availability of paediatric essential medicines in Shaanxi Province, China. Methods: Price and availability data for 28 paediatric essential medicines were collected from 60 public hospitals and 60 retail pharmacies in six areas of Shaanxi Province using a standardised methodology developed by the World Health Organization and Health Action International, during November to December 2012. Affordability was measured as the number of days’ wages required for the lowest-paid unskilled government worker to purchase standard treatments for common conditions. Data on medicine price components were collected from hospitals, wholesalers and distributors to obtain price mark-ups. Findings: The mean availabilities of originator brands (OBs) and lowest-priced generics (LPGs) were 10.8% and 27.3% in the public hospitals and 11.9% and 20.6% in the private pharmacies. The public procurement and retail prices were 2.25 and 2.59 times the international reference prices (IRPs) for three OBs, and 0.52 and 0.93 times for 20 LPGs. In the private sector, the final prices for OBs and LPGs were 3.89 and 1.25 times their IRPs. The final price in the private sector was 2.7% lower than in the public sector for OBs, and 14.1% higher for LPGs. Generally, standard treatments cost less than 1 day’s wages in both sectors. Distribution mark-ups applied to brand salbutamol in Xi'an was 65.5%, and up to 185.3% for generic. Cumulative mark-ups for LPGs in Ankang were also high, from 33% to 50%. The manufacturer’s selling price is the largest contributor to the final price in both areas. Conclusions: The government should approve a list of national paediatric essential medicines. The availability, price and affordability of these should be improved in both public hospitals and private pharmacies to enable children to obtain effective treatment. Measures should be taken to improve the efficiency of the centralised medicine purchasing system

Direct Manipulation of quantum entanglement from the non-Hermitian nature of light-matter interaction

Biphoton process is an essential benchmark for quantum information science and technologies, while great efforts have been made to improve the coherence of the system for better quantum correlations. Nevertheless, we find that the non-Hermitian features induced by the atomic quantum interference could be well employed for the direct control of entanglement. We report the demonstration of exceptional point (EP) in biphotons by measuring the light-atom interaction as a natural non-Hermitian system, in which the electromagnetically induced transparency regime provides a powerful mechanism to precisely tune the non-Hermitian coupling strength. Such biphoton correlation is tuned within an unprecedented large range from Rabi oscillation to antibunching-exponential-decay, also indicating high-dimensional entanglement within the strong and weak light-matter coupling regimes. The EP at the transition point between the two regimes is clearly observed with the biphoton quantum correlation measurements, exhibiting a single exponential decay and manifesting the coalesced single eigenstate. Our results provide a unique method to realize the controllability of natural non-Hermitian processes without the assistance of artificial photonic structures, and paves the way for quantum control by manipulating the non-Hermitian features of the light-matter interaction

Interval Sliding Mode Observer Based Incipient Sensor Fault Detection with Application to a Traction Device in China Railway High-speed

This paper proposes an interval sliding mode observer (ISMO) and an incipient sensor faults detection method for a class of nonlinear control systems with observer unmatched uncertainties. The interval bounds for continuous nonlinear functions and new injection functions are constructed to design ISMOs. An incipient fault detection framework with newly designed residual and threshold generators is proposed. The detectability is then studied, and a set of sufficient detectable conditions are presented. Applications to an electrical traction device used in China Railway High-speed (CRH) are presented to verify the effectiveness of the proposed incipient sensor fault detection methodology

Incipient Fault Detection for Traction Motors of High-Speed Railways Using an Interval Sliding Mode Observer

This paper proposes a stator-winding incipient shorted-turn fault detection method for the traction motors used in China high-speed railways. Firstly, a mathematical description for incipient shorted-turn faults is given from the quantitative point of view to preset the fault detectability requirement. Then, an interval sliding mode observer is proposed to deal with uncertainties caused by measuring errors from motor speed sensors. The active robust residual generator and the corresponding passive robust threshold generator are proposed based on this particularly designed observer. Furthermore, design parameters are optimized to satisfy the fault detectability requirement. This developed technique is applied to an electrical traction motor to verify its effectiveness and practicability