Invasive alien plants in Bangladesh: taxonomic inventory, impact assessment and management issues

The establishment of a database of naturalized species is the first step in understanding the development and spread of invasion, and serves as a stepping-stone for further detailed studies on the biology and impact of individual species on the ecosystem. Preliminary dataset for such a database of Bangladesh is provided here. The inventory of invasive alien flora comprises of 54 species from 48 genera and 24 families. 54% species originate from South America, 17% from Tropical Asia, Tropical Africa and North America - 5% each, Australia and the Mediterranean region - 2% each and China - 1%. With regard to life form representation, herbs constitute the largest share (63%), followed by trees (13%), shrubs (9%), climbers (8%) and grass (7%). Combating plant Invasive Alien Species (IAS) in Bangladesh is very difficult due to the absence of (1) a cataloged list of identified plant IAS, (2) properly carried out case studies on economic and ecological impacts, (3) unstructured programs on management efforts, (4) awareness campaigns and (5) and coordination between different nodal ministries and agencies. As combating IAS requires an integrated approach, all relevant departments must integrate their approaches, establish a national focal point, education and strictly monitor and implement legal instruments.

Rapid Detection of Small Faults and Oscillations in Synchronous Generator Systems Using GMDH Neural Networks and High-Gain Observers

This paper presents a robust and efficient fault detection and diagnosis framework for handling small faults and oscillations in synchronous generator (SG) systems. The proposed framework utilizes the Brunovsky form representation of nonlinear systems to mathematically formulate the fault detection problem. A differential-flatness model of SG systems is provided to meet the conditions of the Brunovsky form representation. A combination of high-gain observer and group method of data handling neural network is employed to estimate the trajectory of the system and to learn/ approximate the fault and uncertainties associated functions. The fault detection mechanism is developed based on output residual generation and monitoring so that any unfavourable oscillation and/or fault occurrence can be detected rapidly. Accordingly, an average L1-norm criterion is proposed for rapid decision making of faulty situations. The performance of the proposed framework is investigated for two benchmark scenarios which are actuation fault and fault impact on system dynamics. The simulation results demonstrate the capacity and effectiveness of the proposed solution for rapid fault detection and diagnosis in SG systems in practice, and thus enhancing service maintenance, protection, and life cycle of SGs.

Some Characterizations of the Extended Beta and Gamma Functions: Properties and Applications

The article represents the elementary and general introduction of some characterizations of the extended gamma and beta Functions and their important properties with various representations. This paper provides reviews of some of the new proposals to extend the form of basic functions and some closed-form representation of more integral functions is described. Some of the relative behaviors of the extended function, the special cases resulting from them when fixing the parameters, the decomposition equation, the integrative representation of the proposed general formula, the correlations related to the proposed formula, the frequency relationships, and the differentiation equation for these basic functions were investigated. We also investigated the asymptotic behavior of some special cases, known formulas, the basic decomposition equation, integral representations, convolutions, recurrence relations, and differentiation formula for these target functions by studying. Applications of these functions have been presented in the evaluation of some reversible Laplace transforms to the complex of definite integrals and the infinite series of related basic functions.

A comparison between analogic and digital media in Engineering teaching

Form representation is essential for any area that involves the creation of artefacts, since without it the project is just an idea in the mental field. In general terms, it is the ability to perceive and understand shapes and represent them through perspectives and orthographic views, as well as through models and geometric models. Given the issues raised, it is possible to understand the importance of knowledge related to the graphic representation of architecture for professionals involved with the Aeco Industry (Architecture, Engineering, Construction and Operation) and, also the relevance of graphic geometry disciplines on the development of Visiographic Three-dimensional Capacity. So, this paper aims to investigate the impact caused by the use of traditional and digital media in the teaching of graphic representation. To this end, two groups of students were compared, one exposed to the use of both media - analogic and digital - and another that used just digital media. From the application of questionnaires, it was possible to identify the student’s profile, their preferences of media and difficulties encountered. The work presumes that students exposed to more disciplines of graphic geometry will have less difficulties compared to those who had less contact. The main results indicated that: there is a preference, in both groups, for digital media to perform practical activities; the need to adapt the content to each specific engineering and that the most significant difficulties were related to work management, regardless of the media used.

Squashed-Slice Algorithm Based on STEP-NC for Multi-Material and Multi-Directional Additive Processes

Even though additive manufacturing is receiving increasing interest from aerospace, automotive, and shipbuilding, the legacy approach using tessellated form representation and cross-section slice algorithm still has the essential limitation of its inaccuracy of geometrical information and volumetric losses of final outputs. This paper introduces an innovative method to represent multi-material and multi-directional layers defined in boundary-representation standard model and to process complex sliced layers without missing volumes by using the proposed squashing operation. Applications of the proposed method to a bending part, an internal structure, and an industrial moulding product show the assurance of building original shape without missing volume during the comparison with the legacy method. The results show that using boundary representation and te squashing algorithm in the geometric process of additive manufacturing is expected to improve the inaccuracy that was the barrier of applying additive process to various metal industries.

Application of Decomposable Semi-Regenerative Processes to the Study of k-out-of-n Systems

This paper aimed to demonstrate the capabilities of decomposable semi-regenerative processes for the investigation of the k-out-of-n system. Proposed in 1955 by W. Smith, the regeneration idea has come a long way in terms of development and has found widespread applications. First, we briefly recall the history of the development of the regeneration idea and the main results of the theory of regenerative, semi-regenerative, and decomposable semi-regenerative processes. Then, the methods of the theory of decomposable semi-regenerative processes are used for the study of a k-out-of-n renewable system with exponentially distributed life and generally distributed repair times of its components. This system is very important for practice and its special cases have previously been considered (including by the authors); however, only special cases and using other methods are considered herein. In the current paper, two scenarios of system repair after its failure are considered for the first time: the partial and the full system repair scenarios. For both scenarios, the time-dependent system state probabilities are calculated in terms of their Laplace transforms. The closed form representation of the stationary probabilities for both scenarios are also presented. These latest results represent a new contribution to the study of this system.

A New One-term Approximation to the Standard Normal Distribution

This paper deals with a new, simple one-term approximation to the cumulative distribution function (c.d.f) of the standard normal distribution which does not have closed form representation. The accuracy of the proposed approximation measured using maximum absolute error (M.S.E) and the same criteria is used to compare this approximation with the existing one-term approximation approaches available in the literature. Our approximation has a maximum absolute error of about 0.0016 and this accuracy is sufficient for most practical applications.

Mass production for mass customization: application of digital fabrication techniques on tower renewal

The opportunity to regain the essence of art and customization in architecture presents itself in a variety of ways if industry becomes open-minded about the potentials our modern technologies bestow. Despite the impact of digital technologies on architectural form, representation, production, and drawing methods, there has been very little innovation in the general flattened rectilinear form of the high-rise due to material innovation and construction methods that evolved out of rationalized techniques and modes of mass production. This thesis investigates ways to re-appropriate surface depth, curvilinear form, variety, and the composition of the high rise cladding by looking at ways that the conventional high-rise envelopes construction and its materials and methods can be manipulated using new design and construction methodologies that have evolved through digital techniques of design and production. The repetitive nature of tower design and the industrial nature of the construction process create an ideal opportunity for the reassessment of this process using post-fordist design and construction methods.

Mass production for mass customization: application of digital fabrication techniques on tower renewal

The opportunity to regain the essence of art and customization in architecture presents itself in a variety of ways if industry becomes open-minded about the potentials our modern technologies bestow. Despite the impact of digital technologies on architectural form, representation, production, and drawing methods, there has been very little innovation in the general flattened rectilinear form of the high-rise due to material innovation and construction methods that evolved out of rationalized techniques and modes of mass production. This thesis investigates ways to re-appropriate surface depth, curvilinear form, variety, and the composition of the high rise cladding by looking at ways that the conventional high-rise envelopes construction and its materials and methods can be manipulated using new design and construction methodologies that have evolved through digital techniques of design and production. The repetitive nature of tower design and the industrial nature of the construction process create an ideal opportunity for the reassessment of this process using post-fordist design and construction methods.