Counterparts In Terms Of Efficiency Research Articles

Halide Substituted Ammonium Salt Optimized Buried Interface for Efficient and Stable Flexible Perovskite Solar Cells

AbstractLow‐temperature solution processing of the perovskite layer enables the fabrication of flexible devices. However, the performance of flexible perovskite solar cells (f‐PSCs) lags far behind their rigid counterpart in terms of efficiency and stability. Emerging evidence demonstrates that the quality of the buried interface between perovskite and transporting layer underneath is the key point. Herein, a class of novel halide substituted ammonium salts, i.e., n‐bromophenethylammonium (n‐Br‐PEAX, n = 2 or 4, X = Cl or Br) are designed and synthesized to modify the buried interface as well as the perovskite crystallization of f‐PSCs. It is found that the ammonium salt with rational design molecular structure can modify the crystallization speed of perovskite, leading to the formation of a compact and uniform morphology without nanovoids at the interface. As a result, the efficiency of f‐PSCs is improved from 15.4% to 20.2%. Moreover, the modified devices without encapsulation retain 86% of their initial performance after 1000 h of aging at ambient conditions and 87% after 290 h of continuous operation.

Output characteristics of none-series compensated inductive wireless power transfer link operating at load-independent-voltage-output frequency

The most important performance merits of inductive wireless power transfer links (IWPTL) operating at load-independent-voltage-output (LIVO) frequency are efficiency and output characteristics. It was recently demonstrated that none-series (NS) compensated IWPTL operating at LIVO frequency outperforms its series-series (SS) and series-none (SN) compensated counterparts in terms of efficiency. In order to complete the comparison, this paper presents output characteristics modeling and analysis (namely, relation between output voltage and load power) of a practical NS-compensated IWPTL operated at LIVO frequency. It is demonstrated that even though the system is operated at LIVO regime, its output voltage remains load-dependent due to practical issues. The lower bound of the output voltage range corresponds to operation under rated loading and is derived using phasor domain equivalent circuit, assuming continuous conduction mode (CCM) of the receiving-side diode rectifier without neglecting equivalent series resistances. On the other hand, upper bound of the output voltage range corresponds to operation under zero loading (inevitably imposing discontinuous conduction mode (DCM) of the receiving-side diode rectifier) and is obtained using time-domain solution of corresponding differential equations system due to the fact that classical phasor analysis fails to accurately describe DCM operating NS-compensated IWPTL. The proposed method is applied to a 1 kW, 400 V NS-compensated IWPTL operated at LIVO frequency and is well-verified by simulations and experiments. Comparison with output voltage characteristics of SS and SN-compensated IWPTLs assert the advantage of NS-compensated topology.

Three-level quantum image encryption based on Arnold transform and logistic map

Quantum computation improves the efficiency and security of cryptography by utilizing characteristics of quantum mechanics. In this paper, a novel three-level quantum image encryption algorithm based on Arnold transform and logistic map is proposed. To obtain satisfactory encryption results, three-level encryption procedures including block-level permutation, bit-level permutation and pixel-level diffusion are performed on the original image. First, the classical plaintext image is transformed into quantum form with novel enhanced quantum representation model. Then, quantum Arnold transform (QArT) is used to scramble the image sub-blocks by processing the qubits that denote position information. By iterating block-level permutation procedure with different block-size and different parameter of QArT, the period defect of QArT can be made up to some extent. Next the bit-level permutation is performed by scrambling the bit-plane order according to a sequence generated with logistic map. Finally, the ciphertext image can be obtained by performing bit-level diffusion through XOR operation between bit-level permutated image and a pseudo-random sequence acquired from logistic map. The corresponding quantum circuits realization are given, and simulations results show that the proposed three-level quantum image encryption scheme has high level of security and outperforms its classical counterpart in terms of efficiency.

Carbon nanotubes to outperform metal electrodes in perovskite solar cells via dopant engineering and hole-selectivity enhancement

Triflic acid dispersed in an apolar solvent exhibited a superior doping effect and stability on carbon nanotube electrodes. The carbon nanotube electrode-based perovskite solar cells exceeded the metal electrode-based counterpart in terms of efficiency.

A new fog based security strategy (FBS2) for reliable image transmission

Fog computing has become a fast intermediate between the cloud and the internet of things (IOT) devices. So, the communication channel between the fog and IOT devices must be secured against attacks. Both Cryptography and steganography are well-known techniques for data security. Each of them has its own advantages and strength points, hence, combining Cryptography and steganography in a hybrid system certainly promotes the system’s level of security. Although several hybrid security strategies have been proposed, they suffer from many drawbacks especially when they are applied in fog environments. Fog computing requires not only high security level but also a real time transmission. Hence, recent hybrid security strategies cannot be applied directly in fog environments as they suffer from long processing time. This paper introduces a new Fog Based Security Strategy (FBS2). FBS2 is a hybrid security strategy as it combines Cryptography and steganography techniques. The proposed Cryptography Technique (PCT) is divided into two phases, namely; confusion and diffusion. The former scrambles the secret image pixels, while the latter changes the pixels values using new confusion and diffusion methodologies respectively. Confusion divides the secret images into closed loops of pixels, then rearrange the pixels into straight paths, while diffusion employs a Programmable Linear Feedback Shift Register (PLFSR). On the other hand, the Proposed Steganography Technique is implemented using the discrete wavelet packet transform. Embedding process depends on a new matching procedure, which is based on the most significant bits of both the encrypted secret image and the corresponding employed cover image pixels. Least significant bits (LSBs) are used as indicators to the matching process. At first an intermediate code is derived from the matching process, then, it is encrypted to represent the LSBs of the stego-image. Experimental results have shown that the proposed FBS2 outperforms the previous counterparts in terms of efficiency, security, and processing time, which proves its suitability for application on the fog.

Simple Surveys: Response Retrieval Inspired by Recommendation Systems

In the last decade, the use of simple rating and comparison surveys has proliferated on social and digital media platforms to fuel recommendations. These simple surveys and their extrapolation with machine learning algorithms such as matrix factorization shed light on user preferences over large and growing pools of items such as movies, songs, and ads. Social scientists also have a long history of measuring perceptions, preferences, and opinions, typically often over smaller, discrete item sets with exhaustive rating or ranking surveys. This article introduces simple surveys for social science application. We ran experiments to compare the predictive accuracy of both individual and aggregate comparative assessments using four types of simple surveys—pairwise comparisons (PCs) and ratings on 2, 5, and continuous point scales in three contexts—perceived safety of Google Street View images, likability of artwork, and hilarity of animal GIFs. Across contexts, we find that continuous scale ratings best predict individual assessments but consume the most time and cognitive effort. Binary choice surveys are quick and best predict aggregate assessments, useful for collective decision tasks, but poorly predict personalized preferences, for which they are currently used by Netflix to recommend movies. PCs, by contrast, successfully predict personal assessments but poorly predict aggregate assessments despite being widely used to crowdsource ideas and collective preferences. We also demonstrate how findings from these surveys can be visualized in a low-dimensional space to reveal distinct respondent interpretations of questions asked in each context. We conclude by reflecting on differences between sparse, incomplete “simple surveys” and their traditional survey counterparts in terms of efficiency, information elicited, and settings in which knowing less about more may be critical for social science.

Innovative Applications and Security of Internet of Things

With the advances and falling cost of intelligent things like RFID/USN, sensor networks, NFC, ZigBee, smart phones, and other relevant technologies, the potential applications and implementations of Internet of things have been intensively studied by both the academia and the industry. One potential application is integrating social networks with IoT, which results in the social Internet of things (SIoT). This vision not only provides potential opportunities but also new challenges. Innovative application and security are two main issues toward this paradigm. This special issue includes five articles covering security issues, powermanagement issue, innovative applications, and integration with social informatics. The study “Framework for NFC-based intelligent agents: a context-awareness enabler for social Internet of things” proposes a framework for developing an NFC-enabled intelligent agent, which combines the NFC technique with context-acquisition, ontology-knowledgebase, and semanticadaptation modules, a credit-based incentive scheme to encourage social cooperation and to recommend relevant services. The resultant social-advertising system shows that this framework can support a wide range of different functionalities and is indispensable to an NFC-based intelligent agent for social Internet of things. The paper “Secure e-health system on passive RFID: outpatient clinic and emergency care” introduces a robust RFID-based e-health system which strengthens the system security, protects the patient’s privacy, and outperforms its counterparts in terms of efficiency. The paper “A case study on the power-aware protocol framework for wireless sensor networks” discusses the challenges of designing power-aware protocols which are capable of operating for long periods of time under harsh conditions. This paper proposes to develop a cross-layer architecture, integrating smart and power-aware protocols at the physical and MAC layers with a low-cost high efficiency power management module (denoting ATON II) which are the basis of long-lasting WSN. The experiments show a longendurance outdoor operation with a low complexity power management unit. The paper “Applying an ontology to a patrol intrusion detection system for wireless sensor networks” proposes a lightweight ontology-based wireless intrusion detection system (OWIDS). The system applies ontology to a patrol intrusion detection system (PIDS). The system constructs the relationship between the sensor nodes in an ontology database to enhance PIDS robustness.The experiments show that OWIDS can reduce intrusion detection system (IDS) energy consumption. The paper “Design and implementation of zigbee-ontologybased exhibit guidance and recommendation system” proposes and implements a new WSN-based application—an exhibit guidance and recommendation system. Taking advantages of Zigbee and ontology, this intelligent and personalized guidance service system overcomes the limitations andweaknesses of conventional guidance systems and provides online user with status monitoring and real-time recommendation service.

Nonprimate lentiviral vectors.

Advances in the nascent field of gene therapy have created a demand for gene transfer vehicles that are capable of safely and stably delivering genes to both dividing and nondividing cells. Retroviral vectors, by virtue of their ability to permanently integrate genes of interest into the target cell genome, have played a prominent role in much of the gene transfer research to date. However, their inability to transduce quiescent cells has rendered them largely ineffective for clinical applications. In contrast, adenoviral vectors are capable of infecting nondividing cells, but attempts to move these vectors into the clinic have been limited at times by their lack of stable expression and high immunogenicity. Lentiviral vectors offer a unique combination of the advantages of these two systems without many of the pitfalls. Lentiviruses can stably transduce both dividing and nondividing cells, and, unlike adenoviral vectors, are not immunogenic in vivo. The most established and tested lentiviral vectors are those based on the human immunodeficiency virus (HIV-1). As a full-length virus, HIV is naturally optimized for production in and transduction of human cells and, as such, has proved an ideal candidate for development into a human gene transfer vector. Concern over the consequences of using vectors based on a pathogenic virus with such an optimized tropism for human cells has, however, limited the clinical applications of HIV vectors. For these reasons, vector development has begun to shift to other members of the lentivirus family that do not infect primates as part of their normal host range. In addition to the potential biosafety benefits, it is possible that some nonprimate lentiviral vectors will show an increased ability to infect some useful cell types relative to HIV-based vectors. As many of these viruses have not been well characterized biologically, an interesting cross-talk has developed where advances in lentiviral biology impact vector development and vice versa. The recent discovery of the central DNA flap in lentiviral genomes and its role in nuclear import of preintegration complexes, for example, may prove critical in bringing the efficiency of nonprimate lentiviral vectors up to the level of HIV vectors. As it appears that these nonprimate vectors might reach parity with their primate counterparts in terms of efficiency and tropism, it must now be considered whether they are truly safer for use in the clinic. This review will focus on those aspects of nonprimate lentiviral biology which make such vectors potentially useful in clinical settings.