Bond breaking with auxiliary-field quantum Monte Carlo

Bond stretching mimics different levels of electron correlation and provides a challenging testbed for approximate many-body computational methods. Using the recently developed phaseless auxiliary-field quantum Monte Carlo (AF QMC) method, we examine bond stretching in the well-studied molecules BH and N$_2$, and in the H$_{50}$ chain. To control the sign/phase problem, the phaseless AF QMC method constrains the paths in the auxiliary-field path integrals with an approximate phase condition that depends on a trial wave function. With single Slater determinants from unrestricted Hartree-Fock (UHF) as trial wave function, the phaseless AF QMC method generally gives better overall accuracy and a more uniform behavior than the coupled cluster CCSD(T) method in mapping the potential-energy curve. In both BH and N$_2$, we also study the use of multiple-determinant trial wave functions from multi-configuration self-consistent-field (MCSCF) calculations. The increase in computational cost versus the gain in statistical and systematic accuracy are examined. With such trial wave functions, excellent results are obtained across the entire region between equilibrium and the dissociation limit.Comment: 8 pages, 3 figures and 3 tables. Submitted to JC

Knowledge of Risk Factors, Symptoms and Barriers to Seeking Medical Help for Cervical Cancer among Omani Women Attending Sultan Qaboos University Hospital

Objectives: This study aimed to assess knowledge and attitudes among Omani woman regarding cervical cancer risk factors and symptoms as well as barriers to them seeking medical help. Methods: This cross-sectional study was conducted between December 2017 and March 2018 at the Sultan Qaboos University Hospital (SQUH) in Muscat, Oman. A validated Arabic-language version of the Cervical Cancer Awareness Measure questionnaire was used to collect data from 550 Omani women visiting SQUH during the study period. Results: A total of 490 women participated (response rate: 89.1%) in this study. Overall, the women demonstrated low levels of knowledge of cervical cancer risk factors and symptoms (28.5% and 45.0%, respectively). The most frequently recognised risk factor was having many children (36.1%), while the most recognised symptom was unexplained vaginal bleeding (69.8%). Women reported that being too scared was the greatest barrier to seeking medical help (68.0%). Various factors were significantly associated with greater knowledge of cervical cancer signs and symptoms including education level (odds ratio [OR] = 2.85; 95% confidence interval [CI]: 1.0–8.22; P <0.05), income (OR = 4.34; 95% CI: 1.70–11.12; P <0.05), parity (OR = 3.59; 95% CI: 1.38–9.36; P <0.05) and a family history of cancer (OR = 1.71; CI: 1.0–2.90; P <0.05). Conclusion: Overall, Omani women demonstrated poor knowledge with regards to cervical cancer; in addition, they identified several emotional barriers to seeking medical help. Healthcare practitioners should reassure female patients to encourage care-seeking behaviour. A national screening programme is also recommended to increase awareness and early diagnosis of cervical cancer in Oman.Keywords: Cervical Cancer; Knowledge; Awareness; Risk Factors; Health Care Seeking Behavior; Women; Oman

On the security of digital signature protocol based on iterated function systems.

A common goal of cryptographic research is to design protocols that provide a confidential and authenticated transmission channel for messages over an insecure network. Hash functions are used within digital signature schemes to provide data integrity for cryptographic applications. In this paper, we take a closer look at the security and efficiency of the digital signature protocol based on fractal maps. This new system can be expected to have at least the same computational security against some known attacks. A Diffie-Hellman algorithm is used to improve the security of the proposed protocol by generating the number of iteration that is used to find the attractor of the iterated function system, which is used to calculate the public key and the signature. The proposed algorithm possesses sufficient security against some known attacks applicable on finite field cryptosystems. They are considered as time consuming to be involved in solving non-linear systems numerically over the defined infinite subfield

A model formulation approach for system support engineering

Organizations today face intense competitive pressure to do things better, faster and cheaper. This pushes organizations to improve their performance over time, while meeting (or catching up with) increased customer demands and competitor pressure. Classical techniques in asset management involve performance monitoring, process control and fault diagnosis techniques that aim to determine the limit of the asset’s service life. Theoretically, replacements should be made at the time when the asset is about to fail so that the full service value of the replaced components can be utilized. However, this is not possible as modern machine systems are of increasing complexity and sophistication. Many other factors govern the operation of the asset. Decisions such as asset replacement, upgrade or system overhaul are in many respects equivalent to a major investment, which is risk sensitive. A high value engineering complex system is expected to be in service for years. Therefore, in order to meet functional demand by the end users, the capability and efficiency of the system should keep increasing. In general, the more complex the systems become, better solutions in both technical and management domains is required. Literature suggests that there is a need to develop a tool or a set of techniques that practitioners in the industry can apply to design support system for operating assets in order to maintain long term optimized performance and best return on investment. This tool should integrate industry domain knowledge to create and deliver a specific support solution for in-service assets, as the circumstance requires. At the moment, there is no generic framework or architecture available for practitioners to use. This leads to the following research question “Can industrial practitioners have generic architecture to simplify the development of such a system”? If the answer is yes; then how possible is it?” This research proposes a validated answer for this important question and discusses the development of the system support engineering (SSE) generic architecture as a fundamental structure for providing a systematic modelling approach that enables industrial practitioners to design, implement and measure a support system performance. The development of such a structure is the result of combining both literature analysis and empirical work. As a result of the above activities, a conclusion is reached that the architecture consists of three elements (product, process and people) in a business environment structured in three levels (Execution, Management and Enterprise). This model is called multi-level 3PE model. The system support engineering approach aims to develop support systems that can sustain constant high performance. The essence of this approach is its ability to capture strategic planning and operation issues by: •  Adapting a whole of systems approach to identify the support system’s requirements. •  Providing a hierarchical structure of three management levels linking support system requirements in one level to requirements in other levels such that the system design can be traceable in the whole system. As a result, operational and commercial issues are integrated in a seamless fashion in the support system. Furthermore, the thesis presents a methodology which industrial practitioners can easily use to evaluate and calculate the performance of a support system. The methodology captures all system support factors in three basic elements, i.e. product process and people in a unified performance scoring process that can be analysed by simple mathematical equation to demonstrate the operational performance of the support system. As main contribution of this research, a generic architecture has been created with the following characteristics: •  Clearly identified requirements. •  An overview of the behaviour vector of the model and clearly drawn relations between elements. •  Captures the strategic decisions, inventions and engineering trade‐offs. •  All activities associated with various phases of the effort at the level of elements in the system breakdown structure.  •  Technical and commercial issues that are linkable from the maintenance and development (expansion) point of view

Fractal attractor based digital signature

Fractal theories are applied to enhance the efficiency and performance of cryptosystem due to their inherent complexity and mathematical framework. A new digital signature scheme based on Iterated Function System (IFS) is proposed, which can reduce computation cost and increase security of the system. The properties of the proposed system are discussed in detail

Response Characteristic of Cable Stayed Bridges under Static Loading and Due to the Earthquakes in Longitudinal Direction

This paper presents the dynamic (earthquake response) analysis of cable stayed bridges under different types of static loading and due to longitudinal directions of earthquake base excitations. The deck and the tower of the bridge were idealized by discrete element idealization scheme (space frame element) with warping considered as a seventh degree of freedom. For comparison purposes, the discrete element with six degrees of freedom (warping neglected) were also used to model the structure under investigation. The cables were modelled by the nonlinear truss elements. It was found that the warping becomes of significant influence on the behaviour of the bridge deck only if the deck is acted upon by loading that is coupled with initial torsional moment

About fuzzy fixed point theorem in the generalized fuzzy fractal space.

The Banach fixed point theorem has applications in several branches of science. Many authors prove this theorem in different types of fuzzy metric spaces and fuzzy fractal spaces. The aim of this paper is to prove the Banach fixed point theorem in a new generalized space called multi fuzzy fractal space

Efficiency analysis for public key systems based on fractal functions.

In the last decade, dynamical systems were utilized to develop cryptosystems, which ushered the era of continuous value cryptography that transformed the practical region from finite field to real numbers. Approach: Taking the security threats and privacy issues into consideration, fractals functions were incorporated into public-key cryptosystem due to their complicated mathematical structure and deterministic nature that meet the cryptographic requirements. In this study we propose a new public key cryptosystem based on Iterated Function Systems (IFS). Results: In the proposed protocol, the attractor of the IFS is used to obtain public key from private one, which is then used with the attractor again to encrypt and decrypt the messages. By exchanging the generated public keys using one of the well known key exchange protocols, both parties can calculate a unique shared key. This is used as a number of iteration to generate the fractal attractor and mask the Hutchinson operator, so that, the known attacks will not work anymore. The algorithm is implemented and compared to the classical one, to verify its efficiency and security. We conclude that public key systems based on IFS transformation perform more efficiently than RSA cryptosystems in terms of key size and key space

IFS on the multi-fuzzy fractal space.

The IFS is a scheme for describing and manipulating complex fractal attractors using simple mathematical models. More precisely, the most popular “fractal –based” algorithms for both representation and compression of computer images have involved some implementation of the method of Iterated Function Systems (IFS) on complete metric spaces. In this paper a new generalized space called Multi-Fuzzy Fractal Space was constructed. On these spases a distance function is defined, and its completeness is proved. The completeness property of this space ensures the existence of a fixed-point theorem for the family of continuous mappings. This theorem is the fundamental result on which the IFS methods are based and the fractals are built. The defined mappings are proved to satisfy some generalizations of the contraction condition