Study on Parameters of Two Widely Used Cohesive Soils Erosion Models

The erosion rate of cohesive soils was typically modeled with the excess shear stress model and the Wilson model. Several kinds of research have been conducted to determine the erodibility parameters of the two models, but few attempts have been made hitherto to investigate the general trends and range of the erodibility parameter values obtained by the commonly used Erosion Function apparatus. This paper collected a database of 177 erosion function apparatus tests to indicate the variability of all erodibility parameters; the range of erodibility parameters is determined by data statistics and parameter theoretical value derivation. The critical shear stress (τc) and erodibility coefficient (Z0) in the over-shear stress model have a positive proportional relationship when the data samples are sufficient. However, there is no such relationship between the erodibility coefficient (b0) and erodibility coefficient (b1) in the Wilson model. It is necessary to express the soil erosion resistance by considering all erosion parameters in the erosion model. Equations relating erodibility parameters to water content, plasticity index, and median particle size were developed by regression analysis.

Ensuring Data Integrity in Databases with the Universal Basis of Relations

The objective of the paper was to reveal the main techniques and means of ensuring the integrity of data and persistent stored database modules implemented in accordance with the recommendations of the Clark–Wilson model as a methodological basis for building a system that ensures integrity. The considered database was built according to the schema with the universal basis of relations. The mechanisms developed in the process of researching the problem of ensuring the integrity of the data and programs of such a database were based on the provisions of the relational database theory, the Row Level Security technology, the potential of the modern blockchain model, and the capabilities of the database management system on the platform of which databases with the universal basis of relations are implemented. The implementation of the proposed techniques and means, controlling the integrity of the database of stored elements, prevents their unauthorized modification by authorized subjects and hinders the introduction of changes by unauthorized subjects. As a result, the stored data and programs remain correct, unaltered, undistorted, and preserved. This means that databases built based on a schema with the universal basis of relations and supported by such mechanisms are protected in terms of integrity.

Why do consumers not switch? An experimental investigation of a search and switch model

Search and switching costs are two market frictions that are well known in the literature for preventing people from switching to a new and cheaper provider. Previous experimental literature has studied these two frictions in isolation. However, field evidence shows that these two frictions frequently occur together. Recently, a theoretical framework has been developed (Wilson in Eur Econ Rev 56(6):1070–1086) which studies the interplay between these two costs. We report on an experiment testing this theory to see if individual behaviour with search and switching costs is in line with the theoretical predictions derived from the optimal choice rule of Wilson. The results show the crucial role of the search strategy: not only, according to Wilson model, the search cost has a greater deterrent impact on search than the switching costs, but also the sub-optimality of the search strategy is the major source of sub-optimality in the switching behaviour.

Analysis of formal models for ensuring data integrity and their applicability to databases

Information systems in general and databases in particular are vulnerable to accidental or malicious attacks aimed at compromising data integrity. Security is easier if you have a clear model that is the formal expression of security policy. The paper explores known security models related to data integrity, their applicability and significance for databases. The analysis of formal models for ensuring data integrity revealed that each of them, having certain advantages and disadvantages, has the right to use. The decisive factor in making a decision is an assessment of a specific situation, which will make it possible to make the right choice, including their complex application. In this regard, the paper notes that the Clark-Wilson model, the undoubted advantages of which are its simplicity and ease of joint use with other security models, is advisable to use as a set of practical recommendations for building an integrity assurance system in information systems. While stating the fact that traditional DBMSs support many of the mechanisms of the Clark-Wilson model, the article points out that implementations based on standard SQL require some compromise solutions. Analyzing the Biba model, the paper concludes about its relative simplicity and the use of a well-studied mathematical apparatus. It is noted that in practice, for the creation of secure information systems, as systems that ensure the confidentiality and data integrity, it is important to unite the Bell-LaPadula and Biba models. Moreover, this union should be on the basis of one common lattice, but with two security labels (confidentiality and integrity) with the opposite character of their definition. This is exactly the variant of combining the Bell-LaPadula and Biba models that is recommended for use in modern information systems and DBMSs, where a mandatory security policy is implemented.

Structural parameters for the globular-cluster-like objects in NGC 1052-DF2

ABSTRACT Recently, van Dokkum et al. have found an ultra-diffuse galaxy NGC 1052-DF2 with little or no dark matter, based on a spectroscopic study of its 11 constituent globular-cluster-like objects. In this paper, we analyse these 11 objects using Hubble Space Telescope imaging. We derive the structural parameters for each object by fitting the surface brightness profiles to three different models. Our results indicate that these objects are better fitted by the Wilson model than by the King and Sérsic models. Using the distance of D = 20 Mpc to NGC 1052-DF2 obtained by van Dokkum et al., these 11 objects have half-light radii in the range from ∼11 to ∼16 pc. These values are much larger than for normal globular clusters in the Milky Way, and are comparable to the sizes of an extended star cluster and of a typical ultra-compact dwarf. The half-light radii obtained here are larger than those obtained by van Dokkum et al. and Trujillo et al. The offset of the differences between the half-light radii of van Dokkum et al. and ours is 6.17 pc, and the offset of the differences between the half-light radii of Trujillo et al. and ours is 4.99 pc. Our half-light radii are, on average, 11.74 pc, which corresponds to 53 and 43 per cent larger than those obtained by van Dokkum et al. and Trujillo et al., respectively. The Rh versus MV diagram shows that these objects occupy the same areas of extended star clusters and ultra-compact dwarfs. Using the distance of D = 13 Mpc obtained by Trujillo et al., there are still five objects that do not lie in the area of normal globular clusters in the Milky Way. So, we suggest that these globular-cluster-like objects in NGC 1052-DF2 are not normal globular clusters like those in the Milky Way.

A Clark-Wilson and ANSI role-based access control model

Purpose An electronic health record (EHR) enables clinicians to access and share patient information electronically and has the ultimate goal of improving the delivery of healthcare. However, this can create security and privacy risks to patient information. This paper aims to present a model for securing the EHR based on role-based access control (RBAC), attribute-based access control (ABAC) and the Clark-Wilson model. Design/methodology/approach A systematic literature review was conducted which resulted in the collection of secondary data that was used as the content analysis sample. Using the MAXQDA software program, the secondary data was analysed quantitatively using content analysis, resulting in 2,856 tags, which informed the discussion. An expert review was conducted to evaluate the proposed model using an evaluation framework. Findings The study found that a combination of RBAC, ABAC and the Clark-Wilson model may be used to secure the EHR. While RBAC is applicable to healthcare, as roles are linked to an organisation’s structure, its lack of dynamic authorisation is addressed by ABAC. Additionally, key concepts of the Clark-Wilson model such as well-formed transactions, authentication, separation of duties and auditing can be used to secure the EHR. Originality/value Although previous studies have been based on a combination of RBAC and ABAC, this study also uses key concepts of the Clark-Wilson model for securing the EHR. Countries implementing the EHR can use the model proposed by this study to help secure the EHR while also providing EHR access in a medical emergency.