We studied spin dynamics of charge carriers in the superlattice-like Ruddlesden-Popper hybrid lead iodide perovskite semiconductors, 2D (BA) 2 (MA)Pb 2 i 7 (with MA = cH 3 nH 3 , and BA = cH 3 (CH 2) 3 nH 3), and 3D MAPbI 3 using the magnetic field effect (MFE) on conductivity and electroluminescence in their light emitting diodes (LEDs) at cryogenic temperatures. The semiconductors with distinct structural/ bulk inversion symmetry breaking, when combined with colossal intrinsic spin-orbit coupling (SOC), theoretically give rise to giant Rashba-type SOC. We found that the magneto-conductance (MC) magnitude increases monotonically with the emission intensity and saturates at ≈0.05% and 0.11% for the MAPbI 3 and (BA) 2 (MA)Pb 2 i 7 , respectively. The magneto-electroluminescence (MEL) response with similar line shapes as the MC response has a significantly larger magnitude, and essentially stays constant at ≈0.22% and ≈0.20% for MAPbI 3 and (BA) 2 (MA)Pb 2 i 7 , respectively. The sign and magnitude of the MC and MEL responses can be quantitatively explained in the framework of the Δg-based excitonic model using rate equations. Remarkably, the width of the MEL response in those materials linearly increases with increasing the applied electric field, where the Rashba coefficient in (BA) 2 (MA) pb 2 i 7 is estimated to be about 7 times larger than that in MAPbI 3. Our studies might have significant impact on future development of electrically-controlled spin logic devices via Rashba-like effects. Organic-inorganic hybrid perovskites (OIHPs) are rapidly emerging as functional materials for novel optoelectronic and quantum electronic devices 1,2. In these materials, strong intrinsic spin-orbit coupling (SOC) stemming from the heavy metal atoms in the inorganic framework (i.e., Pb or Sn) plays a decisive role in significantly lowering the optical band gap down to near the infrared region and preserving optical absorption from perturbations by local distortions of the lattice. These effects have been harnessed to produce high performance solar cells 3. In fact, 3D methylammonium lead iodide (MAPbI 3) OIHP is an excellent material for optoelectronics due to its superb physical properties such as large dielectric constant of above 10 4,5 , long carrier diffusion lengths on the order of 100 μm 6 , high electron/hole mobility of ≈100 cm 2 (Vs) −1 7 , large absorption coefficient as high as 10 4 cm −11 , and small exciton binding energy of a few meV at room temperature 5,8. Recently, the power conversion efficiency for a single-junction OIHP solar cell having an analog of MAPbI 3 as the absorber layer exceeded 25% 9. The high power conversion efficiency observed for these materials may be related to the degree of SOC strength present in their crystal structure. It has been hypothesized that the strong SOC in the absence of inversion symmetry in OIHPs gives rise to Rashba-type effects, where spin-dependent properties can be manipulated by electric fields 10-13. As a consequence, the spin degeneracy in k-space is lifted and the ...

Cloud computing has become a potential resource for businesses and individuals to outsource their data to remote but highly accessible servers. However, the potential of cloud services has not been fully realized due to users concerns about data privacy and security. User-side encryption techniques can be employed to mitigate the security concerns, but once the data is encrypted, no processing (eg, searching) can be performed on the outsourced data. Searchable Encryption (SE) techniques have been widely studied to enable searching on the data while they are encrypted. These techniques enable various types of search on the encrypted data and offer different levels of security. While these techniques enable different search types and vary in details, they share similarities in their components and architectures. In this paper, we provide a comprehensive survey on different secure search techniques, a high-level architecture for these systems, and an analysis of their performance and security level. KEYWORDScloud security, encrypted search, search over encrypted data, survey INTRODUCTIONAs cloud computing becomes prevalent, more cloud-based solutions are being developed and widely used in different applications. Companies that have adopted cloud storage solutions are reported to gain a competitive edge against those that have not. 1Cloud computing is favored due to its many advantages, including convenience and accessibility, consistent back ups to reducing the burden of local storage, and saving capital expenditure on in-house hardware and software maintenance. 2 However, public cloud storage services may be utilized by multi-tenant customers who store large amounts of potentially sensitive data on the cloud. Using cloud storage implies losing full control over data and delegating it to the cloud administrators, exposing the data to potential external and internal attacks, 3,4 which can be devastating for organizations that rely on confidentiality of their data (eg, financial corporations).These problems have made businesses concerned about outsourcing their data to the cloud and utilizing its potential. 5,6 For instance, a medical center that owns patients' health records cannot outsource its data to a cloud that is vulnerable to attacks, due to legal regulations. 7 In another instance, a law enforcement agency that keeps sensitive criminal records will hesitate to use cloud storage because of similar concerns.this approach remains impractical. Therefore, searchable encryption systems (eg, see other works 12-15 ) have been introduced to cope with this problem. These systems ideally allow the encrypted data to be searched without revealing the data and search query. Hence, they relieve concerns about data confidentiality in the cloud. Efforts to create searchable encryption systems date back to 2000 with work by Song et al. 11 Since then, numerous research works have been undertaken to enable different types of searchable encryption. Although these systems differ in their search approaches, security level, and perf...

Undoped and transition metals doped zinc oxide nanorods (ZnO NRs) are prepared onto glass substrates using hydrothermal method. Transition metals (Cu, Ag, Au, Co and Mn) are intended to narrow the optical band gap of ZnO NRs. We have optimised the concentration of metal doping and investigated their structural, morphological and optical properties. The X-ray diffraction (XRD) pattern not only reveals that doped ZnO NRs are well oriented in the (002) plane which corresponds to the hexagonal phase but also confirms that metal ions well replaced ZnO ion in the crystal lattice. The scan electron microscopy (SEM) images show the length, diameter with high density and uniform nanorods. The optical band gap of doped ZnO NRs, calculated from UV-Vis spectra using Tauc's method, exhibits the reduction leading to extension of the optical absorption and shift of the absorption edge toward visible light. More interestingly, the visible absorption is enhanced by decorating metal onto doped ZnO NRs based on the localised surface plasmon resonance (LSPR) effect. Since, multi-modification of ZnO NRs materials could be the foundation for the development of optoelectronic devices using visible light, such as OLED, water splitting, solar cells.

Model predictive control (MPC) has become more attractive in control engineering for the last decades because of its efficiency and robustness. In this paper, an effective control strategy is proposed for vibration reduction of mechanical flexible systems in which establishment of a global dynamic model of the controlled system is not necessary. A modified model-free adaptive predictive controller is designed by combination of MPC and model-free control theory. The novel idea of this contribution is that by using the compact-form dynamic linearization technique, the upcoming system outputs within a specified prediction horizon can be predicted in sequence. The data-based prediction model of the system only requires input/output information, and therefore the future control input increments as well as the unknown system parameters called pseudo-jacobian matrix can be estimated. To improve parameter estimation accuracy, another online estimation method namely recursive least-squares algorithm is applied instead of using the conventional projection algorithm. The control performance is verified nummerically for vibration control of a flexible ship-mounted crane represented as a multi-input multi-output (MIMO) system. Simulation results indicate that significant reduction of the crane oscillations and better control performance are observed when using the proposed controller in comparison with other traditional methods.

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