Pair Of Operators Research Articles

Розрахунок контактного тиску та зони контакту в парах ковзання судових дизелів

Annotation – The durability of marine diesels significantly depends on the operation of friction pairs, such as: piston rings - cylinder liner; crankshaft - bearing shell, plunger - sleeve, and others. This is primarily due to the constant contact interaction of the elements of the friction pairs at different temperatures and load. Therefore, the research of normal pressure and the definition of contact areas in the friction pairs, the studying of the influence of the quality of lubricants on these characteristics are important tasks for predicting the longevity of marine diesels. The solution of these problems is based on the application of mathematical models of processes (numerical simulations) that occur in friction pairs. This considers two main processes that occur during the operation of the friction pairs: the research of contact and tangential stresses that occur in friction pairs in the framework of elastic or elastic-plastic contact models; study of hydrodynamic processes in a thin layer of oil between the elements of the friction pairs. The combination of these processes allows to sufficiently assess the influence of the elastic-mechanical properties of the sliding vapor elements and the viscosity and hydrodynamic characteristics of the oils on the durability of the marine diesel unit. The first process is researched in this work. In particular, for the analysis of contact stresses and contact zones in friction pairs, the method of numerical modeling is used, which is based on the differential equations of the theory of elasticity. With the help of fundamental solutions (influence functions), the problem is reduced to an integra-differential equation with the Gilbert’s kernel. The solution of which is constructed using the method of orthogonal polynomials as well as easy-to-use approximation formulas. Numerical simulations were performed, as a result, the maximum pressure and contact zone parameters for some combinations of friction pairs materials of marine diesel engines were determined. In particular, the influence of the radial gap on the pressure distribution and the size of the contact zone between the elements of the friction pairs of marine diesels is established.

A high throughput biocompatible insulator based dielectrophoretic (iDEP) lab chip for patterning and fusion of biological cells

The ability to precisely pair cells without damaging them has been critical in generating high cell-fusion yields. We present here an insulator-based dielectrophoretic (iDEP) microfluidic lab-chip capable of manipulating ~ 6000 single cells or cell pairs per experimental operation, even with a large variance among the cell population. An ITO glass with a thin PDMS membrane patterned by a lift-off process consisting of a vast array of 6000 holes acts as microwells for pairing and fusion operations. We demonstrate the application of our chip by showing electrofusion between CT26 and bone marrow-derived dendritic cells (BMDC) with fusion efficiencies up to 70% (3000–3500 cells) among paired cells. We extend our study to show that our microfluidic chip is biocompatible and safe from electrical fields by observing properties of fused cells like cell viability of 60% (1800–2200 cells), fluorescence-labeled intracellular materials from CT26 and BMDC, mixed cell morphology over 4 days of culture.

Pairing free asymmetric group key agreement protocol

More and more applications are nowadays distributed and rely on collaborative input. Group key protocols, enabling the construction of a common shared key, are the most evident primitive to efficiently provide the required authentication and confidentiality in the group. Asymmetric group key agreement (AGKA) protocols allow the construction of a common shared public key, where only the participants in the group possessing different private keys are able to decrypt messages encrypted by means of this group public key. Up to now, all the proposed AGKA protocols in literature rely on compute intensive pairing operations, which are too highly demanding for resource constrained devices. We propose in this paper a one-round lightweight elliptic curve based alternative, being able to offer in addition also self-certification to the members of the group due to the usage of Elliptic Curve Qu Vanstone certificates. We show drastic improvements with respect to both communication and computation costs, compared to the pairing based approaches.

Efficient Authentication Algorithm for Secure Remote Access in Wireless Sensor Networks

Wireless sensor networks convey mission critical data that calls for adequate privacy and security protection. To accomplish this objective, numerous intrusion detection schemes based on machine learning approaches have been developed. In addition, authentication and key agreements techniques have been developed using techniques such as elliptic curve cryptography, bilinear pairing operations, biometrics, fuzzy verifier and Rabin cryptosystems. However, these schemes have either high false positive rates, high communication, computation, storage or energy requirements, all of which are not ideal for battery powered sensor nodes. Moreover, majority of these algorithms still have some security and privacy challenges that render them susceptible to various threats. In this paper, a WSN authentication algorithm is presented that is shown to be robust against legacy WSN privacy and security attacks such as sidechannel, traceability, offline guessing, replay and impersonations. From a performance perspective, the proposed algorithm requires the least computation overheads and average computation costs among its peers.

Perspective for the use of industrial waste in lubricating compositions to reduce wear in friction pairs

The article presents an analysis of the mechanisms of lubricating action used to reduce the wear of rails and wheels. A review of lubricant compositions that increase the service life of the wheel-rail pair showed that graphite is the main filler used to create rail lubricants. Since the production of synthetic graphite requires high energy costs, this material is relatively expensive. Replacing graphite with cheaper analogs will help reduce the cost of operating rails without losing lubricating properties in friction pairs. Today, there are many lubricant compositions. Many of them require experimental research since they are based only on theoretical knowledge in the field of tribology. In addition, the adhesion properties of a wheel to a rail depend not only on the action of the lubricant but also on weather and climatic conditions. When choosing a rational lubricant, it is worth focusing on a set of factors, and not only on the properties of an individual filler. The data obtained in theoretical analysis cannot always be verified experimentally. The reasons may be economic inexpediency, the complexity of experimental research, or lack of time. The analysis carried out in the course of this work showed that the study of the effect of lubricant components could be optimized using mathematical and digital modeling. The application of these methods will help to select a rational area for research, simulate the behavior of lubricants containing production wastes, and make the mathematical forecast of the operation of friction pairs more accurate.

Strong key-insulated secure and energy-aware certificateless authentication scheme for VANETs

The rise of vehicular ad-hoc networks (VANETs) brings promise for guaranteeing road safety and improving traffic efficiency. Nevertheless, the pity is that the problems, such as messages authentication and privacy-preserving, that come with it seriously threaten the security and stability of the VANETs. For addressing these problems, in this paper, a pairing-free certificateless signature work for VANETs that supports parallel key-insulated is constructed. On the one hand, the presented work is constructed utilizing the elliptic curve rather than the costly pairing operation. In this way, each vehicle can generate or verify authentication message in a low energy consumption manner. On the other hand, the mechanism of parallel key-insulated is introduced in our proposed work where two helpers alternately assist the users for the periodical key updates, which can not only resist the key exposure but also reduce the risk of the helper’s secret key exposure. Considering possible key exposure in the high dynamic VANETs scenarios, our scheme is more stable and feasible for VANETs environments compared with the existing works. Finally, our work is proved to be strongly key-insulated secure under the discrete logarithm assumption in the random oracle model. Meanwhile, the detailed performance comparisons demonstrate that our work is energy efficient and practical for VANET.

A Four Cumulant-Based Direction Finding Method for Bistatic MIMO Radar with Mutual Coupling

The mutual coupling effects of the transmitter and receiver are known to degrade the performance of direction finding for a bistatic Multiple Input Multiple Output (MIMO) radar system. A four cumulant-combinatorial matrix-based algorithm is proposed to estimate jointly the Direction Of Departure (DOD)and Direction Of Arrival (DOA) of targets under the coexistences of unknown mutual coupling and Gaussian colored noise. Firstly, the multiple groups of four cumulant matrices both on transmitter and receiver are constructed by using the Kronecker product and the banded symmetric Toeplitz characteristics of the mutual coupling matrices. The block four-cumulant matrix is further constructed by combining the transmitter and receiver four cunmulant matrices. Then the new matrix is combined to extract the transmit and receive shift invariance matrices by using the transmitter and receiver four cumulant matrices. The results illustrate that: The proposed method can estimate the DOD and DOA of the targets efficiently in the presence of the strong mutual coupling effect, and parameters are paired automatically without extra pairing operation. The parameter estimation performance of the proposed method is better than those of the existing methods under the strong mutual coupling effect conditions.

All-Electronic Emitter-Detector Pairs for 250 GHz in Silicon.

The spread of practical terahertz (THz) systems dedicated to the telecommunication, pharmacy, civil security, or medical markets requires the use of mainstream semiconductor technologies, such as complementary metal-oxide-semiconductor (CMOS) lines. In this paper, we discuss the operation of a CMOS-based free space all-electronic system operating near 250 GHz, exhibiting signal-to-noise ratio (SNR) with 62 dB in the direct detection regime for one Hz equivalent noise bandwidth. It combines the state-of-the-art detector based on CMOS field-effect-transistors (FET) and a harmonic voltage-controlled oscillator (VCO). Three generations of the oscillator circuit are presented, and the performance characterization techniques and their improvement are explained in detail. The manuscript presents different emitter–detector pair operation modalities, including spectroscopy and imaging.

An Efficient ECC-Based CP-ABE Scheme for Power IoT

The rapid development of the power Internet of Things (IoT) has greatly enhanced the level of security, quality and efficiency in energy production, energy consumption, and related fields. However, it also puts forward higher requirements for the security and privacy of data. Ciphertext-policy attribute-based encryption (CP-ABE) is considered a suitable method to solve this issue and can implement fine-grained access control. However, its internal bilinear pairing operation is too expensive, which is not suitable for power IoT with limited computing resources. Hence, in this paper, a novel CP-ABE scheme based on elliptic curve cryptography (ECC) is proposed, which replaces the bilinear pairing operation with simple scalar multiplication and outsources most of the decryption work to edge devices. In addition, time and location attributes are combined in the proposed scheme, allowing the data users to access only within the range of time and locations set by the data owners to achieve a more fine-grained access control function. Simultaneously, the scheme uses multiple authorities to manage attributes, thereby solving the performance bottleneck of having a single authority. A performance analysis demonstrates that the proposed scheme is effective and suitable for power IoT.

Pairing Free Certified Common Asymmetric Group Key Agreement Protocol for Data Sharing Among Users with Different Access Rights.

Research into a pandemic like Covid-19 needs a tremendous input of patient histories and characteristics. Patients and doctors are only willing to share these sensitive data when they are ensured that the data are solely used by legitimate research laboratories. Asymmetric group key agreement (AGKA) protocols provide a good cryptographic primitive to address this requirement. The AGKA protocols proposed in literature provide users with a common public group key and a different decryption key by relying on compute intensive pairing operations. In this paper, we propose a new primitive, called the Common AGKA (CAGKA) protocol in which the users share the same private-public key pair, resulting in a more efficient solution. By combining Elliptic Curve Qu Vanstone certificates and a recently proposed Canetti–Krawczyk (CK) secure mutual authentication protocol, a one round self-certified pairing free CAGKA protocol is defined, which can be also globally certified after one additional round.

A Lightweight Leakage-Resilient Identity-Based Mutual Authentication and Key Exchange Protocol for Resource-limited Devices

Identity (ID)-based mutual authentication and key exchange (IDMAKE) protocol for client-server environments is a critical cryptographic primitive. Recently, several leakage-resilient IDMAKE (LR-IDMAKE) protocols have been proposed to withstand a new type of attacks, named side-channel attacks. However, the existing LR-IDMAKE protocols have several drawbacks, especially, the performance problem for low-power clients. In this paper, a lightweight LR-IDMAKE protocol well-suited for resource-limited devices is proposed. As compared with the previously proposed LR-IDMAKE protocols, our protocol has the following merits: (1) It is the first lightweight LR-IDMAKE protocol without on-line pairing operation for clients; (2) During life cycle of the proposed protocol, it is resilient to continuous key leakage and has totally unbounded leakage property; (3) Security analysis is formally made to demonstrate that it is strongly secure against adversaries in the continuous-leakage extended-Canetti–Krawczyk (CLeCK) model. Eventually, performance experiences on an IoT device with low-computing power, i.e., the Raspberry PI, are conducted to demonstrate that our protocol is well-suited for resource-limited devices.

Accelerated impurity solver for DMFT and its diagrammatic extensions

We present ComCTQMC, a GPU accelerated quantum impurity solver. It uses the continuous-time quantum Monte Carlo (CTQMC) algorithm wherein the partition function is expanded in terms of the hybridisation function (CT-HYB). ComCTQMC supports both partition and worm-space measurements, and it uses improved estimators and the reduced density matrix to improve observable measurements whenever possible. ComCTQMC efficiently measures all one and two-particle Green's functions, all static observables which commute with the local Hamiltonian, and the occupation of each impurity orbital. ComCTQMC can solve complex-valued impurities with crystal fields that are hybridized to both fermionic and bosonic baths. Most importantly, ComCTQMC utilizes graphical processing units (GPUs), if available, to dramatically accelerate the CTQMC algorithm when the Hilbert space is sufficiently large. We demonstrate acceleration by a factor of over 600 (100) in a simulation of δ-Pu at 600 K with (without) crystal fields. In easier problems, the GPU offers less impressive acceleration or even decelerates the CTQMC. Here we describe the theory, algorithms, and structure used by ComCTQMC in order to achieve this set of features and level of acceleration. Program summaryProgram Title: ComCTQMCCPC Library link to program files:https://doi.org/10.17632/x2gzgm8njh.1Licensing provisions: GPLv3Programming language: C++/CUDANature of problem: In dynamical mean-field theory (DMFT), the computational bottleneck is the repeated solution of a quantum impurity problem [1]. The continuous-time quantum Monte-Carlo (CTQMC) algorithm has emerged as one of the most efficient methods for solving multiorbital impurity problems at moderate-to-high temperatures [2]. However, the low-temperature regime remains inaccessible, particularly for f-shell systems, and the measurement of two-particle correlation functions on an impurity adds a substantial computational burden. The bottleneck of the CTQMC solver is itself the computation of the local trace which includes the multiplication of many moderate-to-large sized matrices. The efficient solution of the impurity, measurement of the two-particle correlation functions, and acceleration of the trace computation are therefore critical.Solution method: ComCTQMC uses the hybridisation expansion of the impurity action to explore partition space [3]. It uses the worm algorithm [4] to explore the union of the partition space with observables spaces, e.g., the two-particle correlation functions. It uses improved estimators to more accurately measure the one- and two-particle Green's functions [5]. Identical impurities are solved across all MPI ranks (for ideal weak scaling) and the trace computations of these impurities are distributed to and accelerated by GPUs (when available). The lazy-trace algorithm [6] is used to further reduce the burden of the local trace calculation.Additional comments including restrictions and unusual features: ComCTQMC solves nearly arbitrary impurities, including those with complex valued and time-dependent interactions. However, there are two restrictions: (1) The retarded part of the interaction is described by a set of bilinears (a paired creation and annihilation operator), and these bilinears must commute with the local Hamiltonian and have real quantum numbers; (2) If a local Green's function vanishes, then the corresponding hybridisation function also vanishes.

An Innovative Approach for Enhancing Cloud Data Security using Attribute based Encryption and ECC

Cloud computing is future for upcoming generations. Nowadays various companies are looking to use Cloud computing services, as it may benefit them in terms of price, reliability and unlimited storage capacity. Providing security and privacy protection for the cloud data is one of the most difficult task in recent days. One of the measures which customers can take care of is to encrypt their data before it is stored on the cloud. Recently, the attribute-based encryption (ABE) is a popular solution to achieve secure data transmission and storage in the cloud computing. In this paper, an efficient hybrid approach using attribute-based encryption scheme and ECC is proposed to enhance the security and privacy issues in cloud. Here, the proposed scheme is based on Cipher text-Policy Attribute Based Encryption (CP-ABE) without bilinear pairing operations. In this approach, the computation-intensive bilinear pairing operation is replaced by the scalar multiplication on elliptic curves. Experimental results show that the proposed scheme has good cryptographic properties, and high security level which depends in the difficulty to solve the discrete logarithm problem on elliptic curves (ECDLP).

Numerical evaluation of the performance of injection/extraction well pair operation strategies with temporally variable injection/pumping rates

In general, in situ remediation techniques require that treatment agents come into contact with contaminants to facilitate the treatment process. Greater contact causes more in situ mixing of the two compounds and greater contaminant reduction. In a recirculation well system featuring an injection/extraction well pair, delivery controls the remedial and economic efficiency of decontamination, and is therefore a key consideration for successful in situ remediation. In this study, we numerically evaluated the remedial and economic efficiency of a recirculation well system with sinusoidal temporally varying pumping and injection rates for enhancing remediation; the results were compared with those of a traditional recirculation well system with constant injection/extraction rates. We performed sensitivity analyses to determine the optimal values of four operational parameters associated with the effects of temporally variable pumping or injection rates on the cumulative swept area of injected chemical amendment for a given operation time or cumulative injected volume, which are good measures of remediation and economic efficiency. The findings of this study provide insight into the mechanical process of plume spreading in response to injection/pumping operational strategies, and demonstrate that enhanced plume spreading is a key requirement for achieving sufficient contact between chemical amendments and contaminants.

A Two-Dimensional DOA Estimation Method Based on Virtual Extension of Sparse Array

The interelement spacing of a coprime array breaks through the half-wavelength limitation, so that a larger array aperture can be obtained with a fixed number of array elements. In this paper, the symmetry of the noncircular signal is used to virtually expand the L-shaped array into an orthogonal cross array. Furthermore, the virtual received signal of the augmented array is obtained by the second-order statistic of the received data. Decoupling and dimension reduction of elevation and azimuth are realized by a z-axis subarray and y-axis subarray. Finally, the sparse reconstruction of the signal is realized by the minimum absolute convergence and selection operator method. This method can enlarge the aperture and freedom of array and has higher accuracy and resolution of DOA estimation. It has the advantages of automatic parameter pairing without additional pairing operation and is effective for coherent and incoherent signals. The final numerical simulation results prove the effectiveness of the method in this paper.

Stable iPEPO Tensor-Network Algorithm for Dynamics of Two-Dimensional Open Quantum Lattice Models

Being able to describe accurately the dynamics and steady-states of driven and/or dissipative but quantum correlated lattice models is of fundamental importance in many areas of science: from quantum information to biology. An efficient numerical simulation of large open systems in two spatial dimensions is a challenge. In this work, we develop a tensor network method, based on an infinite Projected Entangled Pair Operator (iPEPO) ansatz, applicable directly in the thermodynamic limit. We incorporate techniques of finding optimal truncations of enlarged network bonds by optimising an objective function appropriate for open systems. Comparisons with numerically exact calculations, both for the dynamics and the steady-state, demonstrate the power of the method. In particular, we consider dissipative transverse quantum Ising and driven-dissipative hard core boson models in non-mean field limits, proving able to capture substantial entanglement in the presence of dissipation. Our method enables to study regimes which are accessible to current experiments but lie well beyond the applicability of existing techniques.

Lightweight Public Key Authenticated Encryption With Keyword Search Against Adaptively-Chosen-Targets Adversaries for Mobile Devices

Cloud storage services have grown extensively in recent years. For security and privacy purposes, sensitive data need to be outsourced to clouds in encrypted form. Searchable public key encryption (SPKE) enables data ciphertexts to be retrieved by keyword(s) without decryption. Unfortunately, most of the existing SPKE schemes cannot withstand the keyword guessing attack. To combat such attack, public key authenticated encryption with keyword search (PAEKS) was presented. However, the existing PAEKS schemes were proven secure under a designated-targets security model, in which an adversary only can attack a sender and a recipient designated by the challenger. Our cryptanalysis indicates that such a scheme may be insecure against the practical attacks where the adversaries choose their targets by themselves. To fight against adaptively-chosen-targets adversaries, we refine the adversary model for PAEKS by permitting the adversaries to choose their targets adaptively, and then formalize the security definitions under the improved security model. After that, we devise a lightweight PAEKS scheme that avoids the time-consuming bilinear pairing operations and give the security proofs. The comparisons show that it outperforms the existing bilinear pairing-based PAEKS schemes in both the computation and communication performance, and therefore is more suitable for the resource-constrained mobile devices.

Anonymous Authentication and Key Agreement Scheme Combining the Group Key for Vehicular Ad Hoc Networks

Vehicular ad hoc network (VANET) is a multihop mobile wireless communication network that can realize many vehicle-related applications through multitop communication. In the open wireless communication environment, security and privacy protection are important contents of VANET research. The most basic method of VANET privacy protection is anonymous authentication. Even through, there are many existing schemes to provide anonymous authentication for VANETs. Many existing schemes suffer from high computational cost by using bilinear pairing operation or need the assistance of the trust authorities (TAs) during the authentication process or rely on an ideal tamper-proof device (TPD), which requires very strong security assumption. In this study, an anonymous authentication and key negotiation scheme by using private key and group key is proposed, which is based on pseudonym using the nonsingular elliptic curve. In this scheme, there is no third party trust center to participate in the authentication, there is no need to query the database, and there is no need of the local database to save the identity information of many vehicles, which reduce the storage space and the authentication time compared with other schemes. The proposed scheme only needs realistic TPDs. In the proposed scheme, TPDs do not need to preinstall the system key as many other schemes do; hence, the failure of a single TPD does not affect the security of the entire system. The security of the scheme is proved under the random oracle model. Compared with the related schemes using bilinear pairings, the computational cost and communication cost of the proposed scheme are reduced by 82% and 50%, respectively.

Certificateless Privacy Protection Scheme based on Fog Computing in V2G Network

With large-scale electric vehicles connected to the power grid, the security and operating efficiency of V2G networks are facing severe challenges. Aiming at the shortcomings of the existing V2G privacy protection schemes, this study proposes a certificateless privacy protection scheme based on fog computing in V2G network. This scheme applies the elliptic curve certificateless public key signcryption algorithm to the V2G network, avoiding the bilinear pairing operation. At the same time, we introduce the fog calculation model into the charging and discharging data transmission process to design a new V2G network architecture, and used data aggregation technology, which can effectively improve the calculation efficiency. This study compares the security and computational overhead with other existing V2G privacy protection scheme. Compared with other schemes, the security and computational efficiency of the scheme proposed in this article are better.

Secure Outsourced Attribute-Based Sharing Framework for Lightweight Devices in Smart Health Systems

The rapid evolution of the Internet of Things has led to the development of smart health. As a form of medical care that uses advanced Internet technology to realize better diagnosis and treatment of patients, smart health transitions medical services move toward real intelligence and greatly helps users. And in smart health, the secure sharing of personal health records (PHRs) is one of the main concerns of patients and medical personnel. Many attribute-based sharing models have been proposed to secure the sharing of PHRs, but there are still two problems to resolve. One is the potential disclosure of the patient data. The attribute-based model achieves flexible access control, but the access policies contain sensitive information of patients. The disclosure of the policy will lead to the leakage of data of the users. The other is the high computational and storage overhead, particularly in smart health systems with limited computing power. In this article, we present a Smart Health-Lightweight Fine-Grained Sharing (SH-LFGS) framework based on attribute-based encryption (ABE). It achieves a fully hidden access policy by adopting Viéte's formula. SH-LFGS introduces an online/offline mechanism in the PHR encryption phase and the outsourced verifiable decryption mechanism. Because the decrypting test requires only one bilinear pair operation, the SH-LFGS can achieve the task of lightweight computation. Analysis of the performance and security of the proposed model confirm its efficiency and security.