Social Network Analysis: Towards Complexity Problem

Social network analysis is a advances from field of social networks. The structuring of social actors, with data models and involving intelligence abstracted in mathematics, and without analysis it will not present the function of social networks. However, graph theory inherits process and computational procedures for social network analysis, and it proves that social network analysis is mathematical and computational dependent on the degree of nodes in the graph or the degree of social actors in social networks. Of course, the process of acquiring social networks bequeathed the same complexity toward the social network analysis, where the approach has used the social network extraction and formulated its consequences in computing.

Time-Domain Sound Field Reproduction with Pressure and Particle Velocity Jointly Controlled

Particle velocity has been introduced to improve the performance of spatial sound field reproduction systems with an irregular loudspeaker array setup. However, existing systems have only been developed in the frequency domain. In this work, we propose a time-domain sound field reproduction method with both sound pressure and particle velocity components jointly controlled. To solve the computational complexity problem associated with the multi-channel setup and the long-length filter design, we adopt the general eigenvalue decomposition-based approach and the conjugate gradient method. The performance of the proposed method is evaluated through numerical simulations with both a regular loudspeaker array layout and an irregular loudspeaker array layout in a room environment.

Rapid Response! Investigating the Effects of Problem Definition on the Characteristics of Additively Manufactured Solutions for COVID-19

Designers from around the world have proposed numerous engineering design solutions for problems related to the COVID-19 pandemic, many of which leverage the rapid prototyping and manufacturing capabilities of additive manufacturing (AM). While some of these solutions are motivated by complex and urgent requirements (e.g., face masks), others are motivated by simpler and less urgent needs (e.g., hands-free door openers). Previous research suggests that problem definition influences the creativity of solutions generated for it. In this study, we investigate the relationship between the definition of problems related to the COVID-19 pandemic and the characteristics of AM solutions that were openly shared for these problems. Specifically, we analyze 26 AM solutions spanning three categories: (1) hands-free door openers (low complexity problem), (2) face shields (moderate complexity problem), and (3) face masks (high complexity problem). These designs were compared on (1) DfAM utilization, (2) manufacturability (i.e., build time, cost, and material usage), and (3) creativity. We see that the solutions designed for the high complexity problem, i.e., face masks, were least suitable for AM. Moreover, we see that solutions designed for the moderate complexity problem, i.e., face shields, had the lowest build time, build cost, and material consumption. Finally, we observe that the problem definition did not relate to the creativity of the AM solutions. In light of these findings, designers must sufficiently emphasize the AM suitability and manufacturability of their solutions when designing for urgent and complex problems in rapid response situations.

Global adaptive neural backstepping control of a flexible hypersonic vehicle with disturbance estimation

Purpose This paper aims to discuss the precise altitude and velocity tracking control of a hypersonic vehicle, a global adaptive neural backstepping controller was studied based on a disturbance observer (DOB). Design/methodology/approach The DOB combined with a radial basis function (RBF) neural network (NN) was used to estimate the disturbance terms that are generated by the flexible modes of the hypersonic vehicle system. A global adaptive neural method was introduced to approximate the unknown system dynamics, with robust control terms pulling the system transient states back into the neural approximation domain externally. Findings The globally uniformly ultimately bounded for all signals of a closed-loop system can be guaranteed by the proposed control algorithm. Additionally, the command filtered backstepping methods can avoid the explosion of the complexity problem caused by the backstepping design process. In addition, the effectiveness of the proposed controller can be verified by the simulation used in this study. Research limitations/implications Normally lateral dynamics issue should be discussed in the process of control system designed, the lateral dynamics are not included in the nonlinear dynamic model of hypersonic vehicle used in this paper, merely the longitudinal flight dynamics are discussed in this paper. Originality/value The flexible states in rigid modes are considered as the disturbance of the system, which is estimated by structuring DOB with NN approximations. The compensating tracking error and prediction error are used in the update law of RBF NN weight. The differential explosions complexity derived from the backstepping procedure is dealt with by using command filters.

Heterogeneity of recurrences in rectal cancer: application of population models facilitates personalized medicine

Due to heterogeneity in presentation and outcome, patients with metastatic disease cannot be considered a single group. The timing, location and combinations of recurrences determine the feasibility of treatment of the individual patient in an era in which the options for local and systemic treatment have expanded. Studies investigating this complexity are hampered by the lack of both large cohorts and adequate methods. In a well-defined cohort of rectal cancer patients from a randomized clinical trial, with long standardized follow-up, we applied spatial projection models derived from population ecology to overcome the complexity problem. We describe the recurrence patterns in detail and performed stochastic simulation experiments resulting in 1.5 million evaluable patients. The risk of subsequent recurrences was dependent on the presentation of the first recurrent event and decreased with increasing recurrence-free interval. The risk of local recurrence for the median patient (65.8 years, pT3 adenocarcinoma) was threefold increased after the development of rare metastases. The risk of development of rare metastases was increased after the development of other extrahepatic metastases. Our cross-disciplinary approach delivers insights allowing for the development of personalized strategies for (local) treatment of recurrent disease, as well as for surveillance strategies that may potentially impact large patient cohorts. In this proof-of-principle study we demonstrate the feasibility of spatial projection models for cancer research.

Controlling the Complexity of Hierarchical Scheduling Frameworks

Hierarchical scheduling frameworks are a new scheduling paradigm where multiple system schedules are integrated (one-within-another). HSFs presents a multi-layered complexity problem that system engineers are struggling to contain. A promising trend in the aerospace and defense industry is to employ Digital Engineering’s Model-Based Systems Engineering (MBSE) to deal with the complexity of HSFs. MBSE permits the abstraction of application-specific details that can radically speed up system design exploration. Thus, this paper investigates how the output from an HSF algorithm can be converted into an MBSE modeling language that enables architectural exploration for resource allocation. The Unified Modeling Language (UML) Modeling and Analysis of Real-Time and Embedded Systems (MARTE) Profile is the chosen unified modeling language of MBSE. The modeling language is used with an HSF application for demonstration purposes. The approach in this paper seeks to limit tool use by combining an inline verification method (Genetic Algorithm) with a new MBSE workflow.

Quantum blockchain system

Blockchain technology represented by Bitcoin and Ethereum has been deeply developed and widely used due to its broad application prospects such as digital currency and IoT. However, the security of the existing blockchain technologies built on the classical cryptography depends on the computational complexity problem. With the enhancement of the attackers’ computing power, especially the upcoming quantum computers, this kind of security is seriously threatened. Based on quantum hash, quantum SWAP test and quantum teleportation, a quantum blockchain system is proposed with quantum secure communication. In classical cryptographic theory sense, the security of this system is unconditional since it has nothing to do with the attackers’ computing power and computing resources.

A complexity problem for Borel graphs

We show that there is no simple (e.g. finite or countable) basis for Borel graphs with infinite Borel chromatic number. In fact, it is proved that the closed subgraphs of the shift graph on $$[\mathbb {N}]^\mathbb {N}$$ [ N ] N with finite (or, equivalently, $$\le 3$$ ≤ 3 ) Borel chromatic number form a $$\varvec{\Sigma }^1_2$$ Σ 2 1 -complete set. This answers a question of Kechris and Marks and strengthens several earlier results.

A Design Approach Of Mechanical Assemblies Based On MBSE And CAD Models Interoperability

The technological development of the last decades have been able to push human to develop their needs, so a way to new demands were opened and this can lead to a complexity problem. Thereby, a good interoperability between the product design activities can lead to the possibility of ensuring a promising satisfaction to all requirements. However, the major problem is the enormous discontinuity between them. Indeed, each one treats the product from its point of view without recourse to the requirements defined by others. This paper is interested in the collaborative work that brings together the system engineer, who deals with the system from a global view, and the designer, who is a specialist in the detailed design, in order to validate requirements. A new methodology has been proposed to define the role of each one in the design process. This methodology focuses on the product development cycle from the analysis of needs to the validation phase. This obviously requires interoperability between the two domains of Model Based System Engineering (MBSE) and Computer Aided Design (CAD). Based on a pedal bicycle case study which is an industrial mechatronic product, the proposed methodology will be illustrated for validation and highlighting its advantages and limitations.