‘Closing the loop’ in biological systems modeling — From the in silico to the in vitro

This work presents a holistic ‘closed loop’ approach for the development of models of biological systems. The ever-increasing availability of experimental information necessitates the advancement of a systematic methodology to organise and utilise these data. Herein, we present a biological model building framework that maps the treatment of the information from the initial conception of the model, through its experimental validation and finally to its application in model-based optimisation studies. We highlight and discuss current issues associated with the development of mathematical models of biological systems and share our perspective towards a holistic ‘closed loop’ approach that will facilitate the control of the in vitro through the in silico.     

Electromyography-based control of active above-knee prostheses

This paper presents a new electromyography (EMG)-based control approach for above-knee (AK) prostheses, which enables the user to control the prosthesis motion directly with his or her muscle activating neural signals. Furthermore, the unique ‘active-reactive’ control structure mimics the actuation mechanism of a human biological joint, and thus provides the user an experience similar to that of a biological lower limb in the control process. In the proposed control approach, surface EMG is utilized to provide a non-intrusive interface to the user's central nervous system, through which the muscle-activating signals can be obtained. With the EMG signals as inputs, an ‘active-reactive’ control algorithm is developed based on the analysis on a simplified musculoskeletal structure of human biological joint. This control algorithm incorporates an ‘active’ component, which reflects the user's active effort to actuate the joint, and a ‘reactive’ component, which models the reaction of the joint to the motion as a result of the controllable impedance displayed on the joint. With this unique structure, the controller enables the active control of the joint motion, while at the same time achieves a natural interaction with the environment through the modulation of the joint impedance. The effectiveness of the proposed control approach was demonstrated through a set of free swing experiments, in which the user was able to control the prosthesis to follow arbitrary motion commands, and a set of level walking experiments, in which the user achieved natural walking gait similar to the typical walking gait of healthy subjects.     

Bullwhip reduction for ARMA demand: The proportional order-up-to policy versus the full-state-feedback policy

A ‘proportional’ order-up-to policy reacting to ARMA demand is analyzed using stochastic optimal control theory. This policy is compared with a full-state-feedback order-up-to policy. Necessary conditions for an optimum of a weighted sum of the inventory and the ordering variances for both policies are formulated. Based on this a relatively simple expression for the ‘full-state’ policy is derived. The comparison between the two policies demonstrates that the ‘intuitively’ designed proportional policy does not fulfill the objective of controlling both the inventory and ordering variance for all parameter values of the demand model as well as the full-state-feedback policy. The full-state-feedback policy outperforms the proportional policy in several aspects.     

Probabilistic reachability and safety for controlled discrete time stochastic hybrid systems

In this work, probabilistic reachability over a finite horizon is investigated for a class of discrete time stochastic hybrid systems with control inputs. A suitable embedding of the reachability problem in a stochastic control framework reveals that it is amenable to two complementary interpretations, leading to dual algorithms for reachability computations. In particular, the set of initial conditions providing a certain probabilistic guarantee that the system will keep evolving within a desired ‘safe’ region of the state space is characterized in terms of a value function, and ‘maximally safe’ Markov policies are determined via dynamic programming. These results are of interest not only for safety analysis and design, but also for solving those regulation and stabilization problems that can be reinterpreted as safety problems. The temperature regulation problem presented in the paper as a case study is one such case.     

Construction industry offsite production: A virtual reality interactive training environment prototype

The ‘traditional’ construction industry has constantly been challenged to improve its inherent problematic practices. Offsite production (OSP), under the umbrella of modern methods of construction (MMC), has been acknowledged as a means to help improve construction industry performance as well as meet new market demands through the provision of improved, adaptable, and sustainable buildings. However, the deployment of OSP systems, if not managed properly, may adversely affect the end result and be counterproductive. It is therefore imperative that the construction industry stakeholders learn and appreciate the specifics, merits, as well as the risks associated with OSP systems in order to achieve the desired outcomes and consequently improve industry performance.On-the-job-training (OJT) is usually sought to facilitate ‘experiential’ learning, which is argued to be particularly effective where a great deal of independence is granted to the task performer. However, OJT has been criticised for being expensive, limited, and sometimes devoid of the actual training context. In order to address the problems encountered with OJT, several virtual reality (VR) solutions have been proposed. This paper introduces one such VR solution prototype, in order to provide a risk-free environment for learning without the ‘do-or-die’ consequences often faced on real construction projects. The proffered solution provides a unique VR environment for practicing new working conditions associated with OSP practices. While the ‘scenes’ of the VR environment take place on a construction site, the environment predominantly targets professionals, such as project managers, construction managers, architects, designers, suppliers and manufacturers, to allow multidisciplinary learning to occur, and hence overcome ‘knowledge silos’ or ‘knowledge compartmentation’. The VR environment enables unforeseen problems often caused by professionals’ decisions, faulty work, and health and safety issues to occur; where the implications of which can be evaluated in respect of time, cost and resources. The VR environment proposed does not aim to resolve problems associated with OSP per se, rather aims to allow ‘things to go wrong’ and consequently allows users not only to ‘experience’ the resulting implications but also to reflect on those implications as part of the learning process. This paper discusses and presents the prototype for the first development phase of the VR interactive training environment. While the prototype was tested and validated with domain experts from industry, the research community, and academia from different EU countries, the data used in developing the prototype was constrained to one project in the UK which may limit the generalisability of results.     

Barriers in the selection of offshore software development outsourcing vendors: An exploratory study using a systematic literature review

Context

Software development outsourcing is a contract-based relationship between client and vendor organisations in which a client contracts out all or part of its software development activities to a vendor, who provides agreed services for remuneration.

Objective

The objective is to identify various barriers that have a negative impact on software outsourcing clients in the selection process of offshore software development outsourcing vendors.

Method

We have performed a systematic literature review (SLR) process for the identification of barriers. We have performed all the SLR steps such as the protocol development, initial selection, final selection, quality assessment, data extraction and data synthesis.

Results

We have identified barriers such as ‘language and cultural barriers’, ‘country instability’, ‘lack of project management’, ‘lack of protection for intellectual property rights’ and ‘lack of technical capability’ that generally have a negative impact on outsourcing clients. We have identified only one common frequently cited barrier in three types of organisations (i.e. small, medium and large) which is ‘language and cultural barriers’. We did not identify any common frequently cited barrier in three continents (Asia, North America and Europe) and in two decades (1990-1999 and 2000-mid 2008). The results also reveal the similarities and differences in the barriers identified through different study strategies.

Conclusions

Vendors should address frequently cited barriers such as ‘language and cultural barriers’, ‘country instability’, ‘lack of project management’, ‘lack of protection for intellectual property rights’ and ‘lack of technical capability’ in order to compete in the offshore outsourcing business.     

Analysis on the evolution of the discourse on computer software and programming languages in the light of literary genres and POWER-KNOWLEDGE

Although much analyses have been performed on the collaborative nature of software development in papers (7, 8, 9 and 10) with some of them in the perspective of Vygotsky’s Activity theory, less focus has been given on the discursive evolution of software as different ‘Genres’. In this article we will investigate discursive formation of software and the programming languages in course of time driven by increased ‘Activities’, ‘Dialogue’ and ‘Power’ exercised by certain user groups and entities which will complement our efforts with Activity theory and Foucaultdian POWER-KNOWLEDGE. We will show that POWER relation is affecting user preferences, choices and activities, which are producing changes in the programming languages and creating new software genres. We have borrowed the term ‘Genre’ from the literary studies of Bakhtin and applying it for software. The way different coexisting social classes in a specific time in history leave their fingerprints in different speech and text-genres, we claim that similar mechanisms exist in the software world. We will show that a modern software system is developing improved ‘Dialogism’ or ‘Intertextuality’, ‘Chronotope’ ‘Heteroglossia’ and forming its own discourse. Our presentation is heavily dependent on Mikhail Bakhtin’s concept of literary genres and Foucaultdian concept of POWER-KNOWLEDGE.     

Design with part behaviors: behavior model, representation and applications

A part is primarily characterized by its ‘function(s)’. The function of the part is achieved through its ‘interactions’ with other parts in an assembly under a set of operating conditions. These ‘interactions’ constitute the ‘behavior’ of the part. The ‘part behavior’ is achieved through a set of spatial and design functional relationships between the interacting surfaces of the parts. The set of spatial and design functional relationships for a part constitutes the Part Function Model (PFM) of that part. In this paper, the nature and role of part ‘functions’ and ‘behaviors’ have been studied in the context of a product design system. The paper addresses the following issues: (i) relationship between function, behavior, and geometry of a part; (ii) importance of ‘part behavior’ over ‘part function’, and development of a ‘part behavior’ model; (iii) methodology for transforming the part behaviors into the PFM model of the part; (iv) product model framework for storing the PFM model information with an Object Oriented Programming (OOP) based CAD system (Concentra's Concept Modeller); (v) importance of the PFM model within the product development process; and (vi) application of the PFM model for generating various product specifications of the part. The prototype implementation of a Functional Design System for transforming part behaviors into different types of part specifications has also been presented in this paper.     

Landsat urban mapping based on a combined spectral-spatial methodology

Urban mapping using Landsat Thematic Mapper (TM) imagery presents numerous challenges. These include spectral mixing of diverse land cover components within pixels, spectral confusion with other land cover features such as fallow agricultural fields and the fact that urban classes of interest are of the land use and not the land cover category. A new methodology to address these issues is proposed. This approach involves, as a first step, the generation of two independent but rudimentary land cover products, one spectral-based at the pixel level and the other segment-based. These classifications are then merged through a rule-based approach to generate a final product with enhanced land use classes and accuracy. A comprehensive evaluation of derived products of Ottawa, Calgary and cities in southwestern Ontario is presented based on conventional ground reference data as well as inter-classification consistency analyses. Producer accuracies of 78% and 73% have been achieved for urban ‘residential’ and ‘commercial/industrial’ classes, respectively. The capability of Landsat TM to detect low density residential areas is assessed based on dwelling and population data derived from aerial photography and the 2001 Canadian census. For low population densities (i.e. below 3000 persons/km²), density is observed to be monotonically related to the fraction of pixels labeled ‘residential’. At higher densities, the fraction of pixels labeled ‘residential’ remains constant due to Landsat's inability to distinguish between high-rise apartment dwellings and commercial/industrial structures.     

Contextual learning theory: Concrete form and a software prototype to improve early education

In ‘contextual learning theory’ three types of contextual conditions (differentiation of learning procedures and materials, integrated ICT support, and improvement of development and learning progress) are related to four aspects of the learning process (diagnostic, instructional, managerial, and systemic aspects). The resulting structure consists of 15 guidelines which are expected to improve instruction and learning across different situations. The present study was conducted to give concrete form to two general guidelines with respect to differentiation and five guidelines with respect to integrated ICT support. The products were a ‘pedagogical-didactic kernel structure’ and a general software prototype. In collaboration with three preschool teachers in The Netherlands, both products were used to give concrete form to a first guideline on improvement of development and learning progress in practice. This concerned an intake procedure on the estimation and use of children’s entry characteristics by parents and preschool teacher. Information is given about improvement experiences in early educational practice. Further research and development steps are discussed.     

一种实时事务并发控制的新方法:SMVCC

提出了新颖的实时数据库事务并发控制方法：语义多版本并发控制协议（SMVCC）。利用实时数据库中存在多版本数据的特点，考虑实时数据和实时事务语义，结合实时数据库相似性概念，对传统多版本并发控制方法进行扩展，对不同事务采用不同并发控制策略，提高了事务并发度。     

Software engineering education: A study on conducting collaborative senior project development

Project and teamwork training is recognized as an important aspect in software engineering (SE) education. Senior projects, which often feature industrial involvement, serve the function of a ‘capstone course’ in SE curricula, by offering comprehensive training in collaborative software development. Given the characteristics of student team projects and the social aspects of software development, instructional issues in such a course must include: how to encourage teamwork, how to formalize and streamline stakeholder participation, and how to monitor students’ work, as well as sustain their desired collaborative effort throughout the development. In this paper, we present an exploratory study which highlights a particular case and introduces the meetings-flow approach. In order to investigate how this approach could contribute to the project's results, we examined its quantitative benefits in relation to the development of the project. We also conducted focus group interviews to discuss the humanistic findings and educational effects pertaining to this approach.     

Architectural layer recovery for software system understanding and evolution

This paper presents an approach to identify software layers for the understanding and evolution of software systems implemented with any object‐oriented programming language. The approach first identifies relations between the classes of a software system and then uses a link analysis algorithm (i.e. the Kleinberg algorithm) to group them into layers. Additionally to assess the approach and the underlying techniques, the paper also presents a prototype of a supporting tool and the results from a case study. Copyright © 2010 John Wiley & Sons, Ltd.     

Not all wizards are from Oz: Iterative design of intelligent learning environments by communication capacity tapering

This paper presents a methodology for the design of intelligent learning environments. We recognise that in the educational technology field, theory development and system-design should be integrated and rely on an iterative process that addresses: (a) the difficulty to elicit precise, concise, and operationalised knowledge from ‘experts’ and (b) the crucial differences between the communication modalities that experts can relate to, and those that are available to a computer-based system. Inspired by the well-known wizard-of-Oz methodology we discuss the need for characterising and carefully controlling the range of its possible variations. We refer to our approach as ‘tapering’ of the communication capacity of carefully engineered didactical situations and present its application, and a case study from our work with an exploratory environment. We then discuss the generality of the methodology and pragmatic constraints which can be useful in similar research.     

On system rollback and totalized fields: An algebraic approach to system change

In system operations the term rollback is often used to imply that arbitrary changes can be reversed i.e. ‘rolled back’ from an erroneous state to a previously known acceptable state. We show that this assumption is flawed and discuss error-correction schemes based on absolute rather than relative change.Insight may be gained by relating change management to the theory of computation. To this end, we reformulate previously-defined ‘convergent change operators’ of Burgess into the language of groups and rings. We show that, in this form, the problem of rollback from a convergent operation becomes equivalent to that of ‘division by zero’ in computation. Hence, we discuss how recent work by Bergstra and Tucker on zero-totalized fields helps to clear up long-standing confusion about the options for ‘rollback’ in change management.     

一种基于时标的网格事务并发控制方法

定义了一个网格事务模型，提出了支持该网格事务模型的、基于时标的并发控制协议，证明了协议的正确性。该协议扩充了事务类型，减小了事务的冲突范围，从而避免了大量不必要的事务重启，提高了事务的并发度。性能实验分析表明，该协议是可行且有效的。     

Utilization of a systemic business process re-engineering method as a tool to improve software process quality

This paper suggests that a software process can be viewed as an instance of a business process. Therefore software process improvement might be achieved by applying the concepts of Business Process Re-engineering (BPR). BPR is introduced and the recent work of Jacobson, using object-oriented concepts to construct a BPR framework, is described. The paper critiques Jacobson's approach as being essentially reductionist, and presents an alternative approach, State-Behaviour Modelling (SBM), that utilizes systems principles in the analysis of problem situations, while generating object models. The application of SMB to model and improve a component of a software development process, is presented.     

Application of an optimistic concurrency control method

This paper illustrates the implementation feasibility of an optimistic approach to concurrency control. After reviewing the approach and clarifying the underlying algorithms and assumptions, it is applied to the design of a multi-user version of an existing relational database management system. Two different system architectures for a UNIX

1 UNIX is a trademark of Bell Laboratories.

-based environment are presented and prototype implementations have been constructed. We also provide some performance statistics on the optimistic approach to concurrency control and compare it with a traditional locking protocol.     

A historical compilation of software metrics with applicability to NASA��s Orion spacecraft flight software sizing

Estimating the size of a large and complex software system is a challenging task. Early in a project’s life cycle, when requirements for the system may be immature and functionality defined only at a high level, resource profiles are necessary for appropriate funding, staffing, and development of a viable project plan. Similar project historical software size data and trends provide a tool to predict software size, creating a feasible estimation approach. To confidently estimate the flight software required for the Orion Spacecraft, NASA conducted an analysis of similar space and aircraft software systems. This paper presents the results of a study that compiled data from over 400 spacecraft, aircraft, and submarine software projects, which were functionally similar in nature to the Orion spacecraft flight software. The study includes the analysis and summary of overall trends in software size, development strategies, and processes. The results indicate a well-correlated upward trend in software size over time for both crewed and uncrewed space and aircraft. This trend was used to predict the estimated completed size of the Orion flight software at approximately 2.3 million Source Lines of Code (SLOC).     

对象库的并发控制

本文提出了适于工程设计环境的并发控制技术－－动态确认并发控制模式。与传统商业应用相比,该环境中的事务持续时间一般很长,因此它需要新的并发控制技术。动态确认是乐观的并发控制模式,避免了对数据长时间的上锁。它产生的操作是“关于数据库可串行化的”,即认为只要产生相同结果,则该调度就和从同一初始数据库状态开始执行的事务串行操作等价。显然,这个串行化标准是弱于通用串行化标准的。