Timing constraint specification and synthesis in behavioral VHDL

A representation for specifying the timing constraints of real‐time systems is presented. Four parts of descriptions in a timing constraint: the path of events, timer, types of constraints and quantities of time, are explained. Under the relations among the paths, the hierarchical and network structures can be conducted. The former can be associated with the structure resulting from applying top‐down decomposition in software development. The latter represents the execution dependence of the paths. Based upon these clear and manageable structures, the completeness and consistency of timing constraints specification can be rigorously analysed. Thus, the quality of the specification of timing constraints can be improved during software development. A frame‐like software requirements specification language (FSRSL) is extended to specify timing constraints and the related descriptions in the paper.

Deceptive path planning (DPP) aims to find a path that minimizes the probability of the observer identifying the real goal of the observed before it reaches. It is important for addressing issues such as public safety, strategic path planning, and logistics route privacy protection. Existing traditional methods often rely on “dissimulation”—hiding the truth—to obscure paths while ignoring the time constraints. Building upon the theory of probabilistic goal recognition based on cost difference, we proposed a DPP method, DPP_Q, based on count-based Q-learning for solving the DPP problems in discrete path-planning domains under specific time constraints. Furthermore, to extend this method to continuous domains, we proposed a new model of probabilistic goal recognition called the Approximate Goal Recognition Model (AGRM) and verified its feasibility in discrete path-planning domains. Finally, we also proposed a DPP method based on proximal policy optimization for continuous path-planning domains under specific time constraints called DPP_PPO. DPP methods like DPP_Q and DPP_PPO are types of research that have not yet been explored in the field of path planning. Experimental results show that, in discrete domains, compared to traditional methods, DPP_Q exhibits better effectiveness in enhancing the average deceptiveness of paths. (Improved on average by 12.53% compared to traditional methods). In continuous domains, DPP_PPO shows significant advantages over random walk methods. Both DPP_Q and DPP_PPO demonstrate good applicability in path-planning domains with uncomplicated obstacles.

Modular design is a key challenge for enabling large-scale reuse of hardware modules. Unlike software, however, hardware designs correspond to physical circuits and inherit constraints from them. Timing constraints—which cycle a signal arrives, when an input is read—and structural constraints—how often a multiplier accepts new inputs—are fundamental to hardware interfaces. Existing hardware design languages do not provide a way to encode these constraints; a user must read documentation, build scripts, or in the worst case, a module’s implementation to understand how to use it. We present Filament, a language for modular hardware design that supports the specification and enforcement of timing and structural constraints for statically scheduled pipelines. Filament usestimeline types, which describe the intervals of clock-cycle time when a given signal is available or required. Filament enablessafe compositionof hardware modules, ensures that the resulting designs are correctly pipelined, and predictably lowers them to efficient hardware.

We study the problem of providing real-time service to hard and soft real-time messages in wavelength division multiplexing (WDM) optical networks. We propose and evaluate a set of scheduling algorithms which schedule message transmissions in single-hop WDM passive star networks based on specific time constraints. We compare the performances of our algorithms with that of the typical WDM scheduling algorithm which does not consider the time constraint of the transmitted messages by discrete-event simulations and an analytical model. We find that the improvement on real-time performance can be attributed to our scheduling algorithms where the time constraint of messages has been taken into consideration. This study suggests that when scheduling real-time messages in WDM networks, one has to consider not only the problem of resources allocation in the network but also the problem of sequencing messages based on their time constraints.

Specification and verification of timing properties is a critical but error-prone issue in the development of real-time systems. Event-B is a formalism with the aim of modeling and analyzing systems. But it does not directly support the modeling of timing properties. Several studies have extended Event-B to formalize timing properties. These works are mainly concerned with timing constraints between events without the consideration of task-level timing constraints. In this paper, we propose patterns for task-level timing constraints precedence and coincidence. Firstly, we introduce the pattern for task deadline that states timing properties within a task. Then patterns for precedence and coincidence are built on top of this one. Furthermore, we illustrate the application of proposed patterns through the formal development of an example. It shows that the patterns can be integrated with Event-B models smoothly by the refinement. Our patterns can be potentially applicable to a wide range of modeling safety critical real-time systems. Additionally, our work provides a reference for the specification of other task-level timing constraints, e.g., exclusion and sub-occurrence.

This study investigates the use of science-based experimental methods to enhance creativity in early childhood at RA Roihanul Jannah. The research involved 31 students actively engaging in science learning through experiments. A qualitative approach was adopted, focusing on Group B teachers and the principal as informants. Data were collected through observation, interviews, and documentation from July to August 2024. The findings indicate that the experimental method effectively promotes scientific understanding, curiosity, and problem-solving skills among children. It also enhances fine and gross motor skills through hands-on activities. However, challenges include the need for specific materials and time constraints. The study concludes that incorporating experimental methods in early childhood education significantly fosters creativity and engagement in science.

In this paper, we focus on tasks offloading over two tiered mobile cloud computing environment. We consider several users with energy constrained tasks that can be offloaded over cloudlets or on a remote cloud with differentiated system and network resources capacities. We investigate offloading policy that decides which tasks should be offloaded and determine the offloading location on the cloudlets or on the cloud. The objective is to minimize the total energy consumed by the users. We formulate this problem as a Non-Linear Binary Integer Programming. Since the centralized optimal solution is NP-hard, we propose a distributed linear relaxation heuristic based on Lagrangian decomposition approach. To solve the subproblems, we also propose a greedy heuristic that computes the best cloudlet selection and bandwidth allocation following tasks' energy consumption. We compared our proposal against existing approaches under different system parameters (e.g. CPU resources), variable number of users and for six applications, each having specific traffic pattern, resource demands and time constraints. Numerical results show that our proposal outperforms existing approaches. We also analyze the performance of our proposal for each application.

Modeling embedded real time systems consisting of different components with UML-RT leads to a design model using various diagrams. Sequence diagrams describe possible interactions between system components and may be annotated with specific real time constraints. Statechart diagrams are used for describing each component's behavior. In order to be able to get a consistent model, a consistency concept for different diagram types is needed that takes into account real time constraints. A consistency concept for sequence diagrams and statechart diagrams is presented which focuses on the establishment of timing constraints. Our consistency concept distinguishes between syntactical, semantic and real time consistency and takes into account the influence of processor allocation and scheduling. Using the consistency concept, we describe a method for ensuring the consistency based on worst case execution time analysis of statecharts and schedulability analysis of tasks, thereby enabling a precise answer to the question of consistency.

The model-driven software development for hard real-time systems promotes the usage of the platform independent model as major design artifact. It is used to develop the software logic at a high level of abstraction and enables analysis like for example model checking of critical model properties. Ideally, starting with the platform independent model, the platform specific model serves only as an intermediate artifact which is derived automatically, and will finally result in a set of threads whose implementations guarantee the behavior, specified in the platform independent model. However, the current MDA approaches and tools for hard real-time software do not provide this ideal: While some of the MDA approaches could in principle support this vision, most approaches simply do not support an appropriate specification of time constraints in the platform independent model which have to be respected in the platform specific model or in the code. This is also true for UML models and UML State Machines in particular. Our approach overcomes those UML specific limitations by firstly proposing a syntactic extension and semantic definition of UML State Machines which provides enough details to synthesize an appropriate platform specific model that can be mapped to code for hard real-time systems automatically. Secondly, a new partitioning algorithm is outlined, which calculates an appropriate mapping onto a platform specific model by means of real-time threads with their scheduling parameters which can be straight forward transformed to code for the hard real-time system.KeywordsModel CheckModel Drive ArchitectureMain ThreadModel Drive ArchitectureTime GuardThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper explores the intersection of new speakers in conditions of globalisation led mobility and it investigates the implications the phenomena may have for language policy making. It first describes two historical phases in language policy development that are closely related to a sociolinguistics of stability. In this, it criticises how present-day language policy is attached to specific time and space constraints whose focus is a by now outdated concept of language and of speaker as its prescriptive objects—thus leading institutional language policies to not being ‘in sync’ with contemporary new speakers’ socio- and geo-political movements and developments. This proposition is illustrated in two case studies, both located in the Netherlands and dealing with the language practices and connected policies of two types of new speakers. The first case deals with the experiences of asylum seekers being engaged with ‘techno-literacies’. That is asylum seekers being part of ICT assisted classes for civic integration through the learning of Dutch (new speakers of a new language, learning through new means of language learning). The second case deals with Chinese students who are fully proficient in Dutch, attending language heritage classes for learning Mandarin through book based lessons (new speakers of an old language, learning through old means of language learning). In both cases, the observed language practices and meta-pragmatic judgements of the individual language users elect them as initiators of bottom-up sociolinguistic change that, while offering grassroots solutions for local challenges, also plays a role as local evidence for informing future top-down language policy development.

Train delays have a great impact on the schedule of high-speed railways including overall efficiency and the quality of the travel service of the passengers. Therefore, the development of an approach to recover a schedule via timely and rapid operation adjustments must be investigated. In this paper, a complete final real-time adjustment scheme is proposed for the train dispatcher of a railway enterprise for delayed trains. A train operation process model based on the Max-Plus algebra method is proposed. Six operation adjustment strategies are analyzed including section acceleration, operation based on the original timetable, dwell time reduction, increase in overtaking, reduction in overtaking, and train postponement. An approximate model is then built based on the minimum number of delayed trains considering the constraints of the adjustment strategies and the feasible adjusted schemes can be quickly obtained without any record specific time data and constraints. The set of feasible solutions of the approximate model is then regarded as the importation of the second model. In addition, the second model is an optimization model for operation adjustment with the least average delay time of each train at each station by updating the state matrixes of the train operation process model. The algorithms are designed for these models, and this approach can reduce the computation time. Finally, the timetable of the Beijing-Shanghai high-speed railway is considered as the actual case for analysis. Thus, the method was proven feasible for operation adjustment of delayed trains.

PurposeTo evaluate and optimize asphalt paving operations taking place in the reconstruction project of Interstate 74 in the USA using simulation.Design/methodology/approachData collected during construction was used to determine useful probabilistic density functions for the activities duration and to validate a developed simulation model. Upon validation, the developed model was used to study the impact of resources on the flow of operations, and on the cost‐effectiveness of the construction process.FindingsThe developed simulation model was successful in simulating the paving operation and its accuracy was acceptable compared to field measurements. Based on the results of a sensitivity analysis of the critical resources, multiple factors were identified in the decision‐making process to ensure that all aspects of the operation were considered. For the conditions pertinent to this construction site, 30 trucks, one paver, and two rollers are recommended. Using this set of resources results in a prompt and effective execution of the construction process.Research limitations/implicationsThe developed model is applicable only to asphalt paving operations. The predictive capability of the developed model has not yet been investigated.Practical implicationsImplementation of the presented model in practical applications can be accomplished by conducting short training courses. This will provide personnel with flexibility in addressing project‐specifics conditions and limitations. If this approach is not feasible, production charts may be developed to easily determine the optimum resources that should be used given specific time constraints and quantity, issues.Originality/valueThe presented methodology has great potential to optimize resources and production rates in similar asphalt paving operations. Moreover, benefits of simulation would be maximized if it was used during the planning phase, as it will affect equipment orders and material shipments.

Highly efficient algorithms for solving the time constrained shortest path problem have been highlighted over the past decades to reduce the cost of vehicle travel in the road network. The paper presents a novel graph algorithm comprising three stages to acquire a time constrained shortest path between any two nodes on the map. In the first stage, the undirected graph is transformed into a directed graph (DT graph) by deleting edges that must not be included in any of the time constrained shortest paths. A variant DT tree with the destination as the root and the source as the leaf is then constructed from the DT graph in the second stage. By finding the minimal difference value between leaves and the root of the variant DT tree, we can eventually obtain a time constrained shortest path from the variant DT tree in the third stage. Experimental results show that our algorithm not only requires less running time than some classical graph algorithms but also can work immediately in the first stage without knowing the information of both the destination and a specific time constraint.

Indoor spaces are fundamentally different from outdoor spaces in terms of the lack of vistas and restrictions on movement. Past literature on how individuals build indoor spatial knowledge over time through extended navigation routes is reviewed. New virtual reality studies on learning indoor spaces using either simple routes or complex routes under either motivated conditions or control conditions are presented. Participants in the motivated group were encouraged to perform the task as quickly as possible, while the control group was under no specific time constraints. Both groups were then tested on their ability to follow schematized instructions to explore unfa- miliar areas in the virtual reality environment. Performance of the various spatial tasks across the motivated and control groups indicated that motiva- tion improved performance in all but the most complex conditions. Results of the research suggest to those who design built environments and future wayfinding systems the importance of considering route complexity and knowledge and affect of the traveler.

Despite the fact that non-interactive Internet multimedia applications are prevalently deployed via HTTP/TCP, dedicated real-time protocols remain the essential basis for interactive voice and video services. This is particularly pronounced by the standardization of WebRTC, which enables peer-to-peer realtime communication between web browsers via the RTP protocol suite. However, a compound solution that contributes error and congestion control for RTP-based communications services is missing by now. In our previous work we presented a novel transport protocol - Predictably Reliable Real-time Transport (PRRT) - a protocol layer that efficiently supports the reliability required by interactive multimedia services under their specific time constraint. In the following paper we integrate PRRT's workflow and header format into a bi-directional RTP session by enhancement of the profile for generic forward error correction. We particularly focus on a low messaging overhead and the preservation of backward compatibility in the protocol's error control.