Delay Analysis Method Research Articles

Enhanced Real-time Scheduling of AVB Flows in Time-Sensitive Networking

Time-Sensitive Networking (TSN) realizes high bandwidth and time determinism for data transmission and thus becomes the crucial communication technology in time-critical systems. The Gate Control List (GCL) is used to control the transmission of different classes of traffic in TSN, including Time-Triggered (TT) flows, Audio-Video-Bridging (AVB) flows, and Best-Effort (BE) flows. Most studies focus on optimizing GCL synthesis by reserving the preceding time slots to serve TT flows with the strict delay requirement, but ignore the deadlines of non-TT flows and cause the large delay. Therefore, this paper proposes a comprehensive scheduling method to enhance the real-time scheduling of AVB flows while guaranteeing the time determinism of TT flows. This method first optimizes GCL synthesis to reserve the preceding time slots for AVB flows, and then introduces the Earliest Deadline First (EDF) method to further improve the transmission of AVB flows by considering their deadlines. Moreover, the worst-case delay (WCD) analysis method is proposed to verify the effectiveness of the proposed method. Experimental results show that the proposed method improves the transmission of AVB flows compared to the state-of-the-art methods.

Analysis and Synthesis of Cooperative Adaptive Cruise Control Against the Hetero-Integration Poly-Net Loop Delays

Cooperative Adaptive Cruise Control (CACC) is a promising technology for improving the capacity and energy efficiency of the ground transportation system. In this paper, a novel CACC control scheme is proposed to deal with the adverse impacts of both inter- and intra-vehicle network delays. First, a hetero-integration poly-net (PN) loop delay analysis method is presented to clarify the system delays in CACC considering both inter- and intra-vehicle network influences. A mathematic equation is put forward to calculate the upper bound of the PN loop delays. Then a collaborative software-defined network scheme is presented to deal with the PN loop delays, which consists of the application/strategy, network-control and network-data planes. In the network-control plane, a fraction-type basic period scheduling method is adopted. In the application/strategy plane, a delay-tolerant model predictive controller is designed for decision-making while a combination of an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_∞</i> controller and a linear quadratic regulator is adopted for acceleration tracking control against local intra-vehicle network delays. Finally, the proposed scheme is verified under a variety of scenarios based on comprehensive Hardware-in-the-Loop tests.

RULE-BASED DELAY ANALYSIS SELECTION SYSTEM

Since the selection of a delay analysis method depends on the delay analyst's subjective judgment, there is a risk of making problematic decisions due to the delay analyst's ignorance, lack of experience, carelessness, or intention. Each one of these methods may yield different analysis results. Therefore, it is necessary to develop an objective decision-making system based solely on the project environment. The existing delay analysis methods are classified into four types, according to the basic principles used in the analysis. Seven conditions that affect the selection of a delay analysis method (i.e., type of schedule, type of information, timing of analysis, expectations from the delay analysis, acceptance by courts of law, capabilities of delay analysis team, and budget constraint) were identified in a literature review. A delay analysis selection system (DASS) was developed using if-then rules constructed by considering which conditions should exist in a given project environment for successfully performing a specific type of delay analysis and getting realistic results. This system was computerized and validated by implementing it in several but different scenarios considered in this study. The contributions of this study include (1) an objective selection decision can be made based on only the project environment, without relying on the analyst's subjective preference, and (2) unnecessary and expensive legal disputes caused by delay-related issues between construction owners and construction companies can be minimized.

INDISPENSABLE DELAY ANALYSIS METHOD SELECTION: AN INTEGRATED AHP-RII APPROACH

A delay is an inevitable event in construction projects due to their intricacy and dynamic nature, therefore, the project parties frequently come to disputes about which party is liable for schedule delays. Delay analysis methods are gradually evolved and are used to steadily determine and apportion delay’s responsibilities. Notwithstanding, courts and arbitrary boards have not legalized any specific standard category of delay analysis technique to timely evaluate the impact of activity(es) delay on to total project duration. Also, there is no universal delay analysis method that can be used better than the others under certain circumstances. This research, thus, targets to seek the most appropriate and fundamental DAM for delay claims resolution. The study methodology adopted in the research by conducting an extensive literature review to identify current delay criteria which have much more impact on the selection of delay analysis method than existing delay analysis method is also carried out for an efficient discussion with a panel of experts. An Integrated Analytical Hierarchy Process and Relative Importance Index (AHP-RII) approach is ideally employed to analyze the highest and the most priority delay analysis method along with the critical factor weight influencing detecting the most proper type of delay analysis. Study findings are very authentic by fairly selecting the best delay analysis method based on reliable delay factors and available delay analysis methods. The researchers and practitioners may yield viable study outputs for incipiently practical preparation of a variety of data and documents which can be publicly supported as active and valid evidence for future claims.

Autonomous Emergency Braking of Electric Vehicles With High Robustness to Cyber-Physical Uncertainties for Enhanced Braking Stability

Modern autonomous emergency braking (AEB) system is a typical safety-critical cyber-physical system (CPS) synthesizing the vehicular communications, control, and proception technologies. However, the control performance of braking can be easily deteriorated by the road adhesion saturation in physical environment and the multi-hop communication network-induced delays in cyber systems. Motivated by this, a new multi-hop loop delay analysis method and its associated upper-bound expression is proposed to scrutinize the system uncertainties, within the scope of CPS. Following this endeavor, a hierarchical cyber-physical control scheme for the AEB system is proposed to mitigate the adverse effects of road adhesion saturation and multi-hop communication network-induced delays. At the upper layer, a μ-adaptive time-to-collision (TTC) planning strategy is adopted to generate the desired acceleration for collision risk avoidance considering the road adhesion saturation. At the lower layer, an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> -based linear quadratic regulator (LQR) is designed for acceleration tracking with strong robustness to the uncertainties of cyber system. Hardware-In-Loop (HIL) experiments validate that the proposed method is superior in terms of braking accuracy and the robustness to the system uncertainties.

Theory and application of growth delay analysis of colony formation for evaluation of injured population of the stressed fungal conidia.

A new concept of injured population assessment is proposed, in which the size of the injured population in stressed mold spores is evaluated by analyzing the colony formation process on a solid agar medium. In this method, a small paper disc containing mold spores is placed on a subculture agar plate, and the linear increase in the radius of the colony formed by development from the spore is measured over time. Then, the principle of the previously reported growth delay analysis (GDA) method originally using a liquid medium is applied to obtain the integrated viable ratio (IV) of the stressed population from the delay time relative to the growth of the unstressed population. On the other hand, the viable ratio (V) to the initial value as the colony count obtained with the stressed culture is obtained; the difference between the logarithms of V and IV is determined as the log number of the injured population. Applying this analysis method to heated spores of Cladosporium sphaerospermum, we determined the size of the injured population that occurred. This method was considered to be effective as a new method for quantifying injured populations using a solid medium.

New Delay-Analysis Method Using Modified Schedule and Modified Updated Schedule for Construction Projects

New Delay-Analysis Method Using Modified Schedule and Modified Updated Schedule for Construction Projects

EFFECTIVE CRITERIA FOR SELECTING DELAY ANALYSIS METHODOLOGIES FOR CONSTRUCTION PROJECT IN ABU DHABI

This paper examines the effective criteria to determine the capable delay analysis methodologies by the contractors for the construction’s claim in Abu Dhabi. The previous research was argued that 50% of the construction projects in UAE encounter delays and are not completed on time. Selecting the delay analysis methodology is a significant part of the claim process. Numerous delay analysis techniques used in the UAE, and constitute several factors. Thus, the selection practice is more significant to identify the delays. Contractor’s analyst consumed exaggerated time and effort to show their right using delay analysis methodologies (DAMs) and submit this as an extension of time claim, demanding to make the most of their benefits. The aim of this study contains exploring the selection of the delay analysis methodologies by the contractors for the construction’s claim in Abu Dhabi. In this regard, five case studies were selected on the basis that they represent examples for application of the delay analysis methods and techniques for the residential building. The respondents were selected from five projects and the interviews were held with the Contractor of each project. The collected Qualitative Data was analysed manually by using Thematic Analysis. The study found that the effective criteria for determining the delay analysis methodologies lie in its acceptance in court and as per contractual requirements. Furthermore, the factors influence the selection of the effective criteria for determining the delay analysis methodologies are the acceptance of the selected delay analysis method /technique, realistic results and accuracy of the delay analysis method /technique. However, the findings from this study become more important, if more studies are conducted to extend the exploring of the different delay analysis methodologies used by the contractors for the construction’s claim for wide range of projects in Abu Dhabi.

Detecting the most appropriate delay analysis methods for mega airport projects

PurposeThis study aims to detect the most appropriate delay analysis method in mega airport projects.Design/methodology/approachFirst, the criteria affecting the selection of delay analysis methods were detected through an in-depth literature review and an expert panel, which was conducted with 12 experts who have experience in delay analysis domain in mega airport projects. Later, fuzzy VIKOR (VIsekriterijumska optimizacija i KOmpromisno Resenje) approach was conducted by considering the detected selection criteria and the most common delay analysis methods.FindingsWindows Analysis method was detected as the best option for mega airport projects. It was followed by Time Impact Analysis (TIA), collapsed as-built analysis, as-planned vs as-built method and impacted as-planned method, respectively.Originality/valueEach project has its own characteristics and thus requires specific management techniques; therefore, selecting a delay analysis method without considering the project types and size may cause conflicts between the contracting parties. On the one hand, numerous fruitful studies concerning delay analysis methods have been conducted in the literature, but on the other hand, none of them has considered project characteristics in terms of project size and type while selecting the most appropriate delay analysis method. Moreover, the larger the size of a project is, the more vulnerable it is to encounter with delays. Mega airport construction projects are complex in their nature in that they are large size and involve multi-disciplinary processes; thus, they need special attention in the process of resolving delays. This study intended to fill this gap in the literature by focusing on selection of the most appropriate delay analysis method for mega airport projects, and it is clear that considering the project type and size in the selection of delay analysis methods will provide more reliable outcomes.

Delay Analysis Statements in the Presence of Debatable Concerns in Construction Projects

Construction projects are usually suffering from the risk of delayed completion. Consequently, Delay analysis is used to evaluate and apportion the effects of delays on the project schedule and thus liabilities can be assigned. This paper introduces the available delay analysis methods along with their capabilities and limitations. Also, the research provides a guide for selecting the appropriate delay analysis method. Yet, analysis of schedule delay events may be influenced by some debatable issues, including float ownership, concurrency, pacing delays, and accelera-tion. This paper represents these issues, which reveal that there exists a gap in handling such analysis. Hence, a questionnaire is designed, which intends to raise the awareness of practition-ers and propose the idea of standardizing the project decisions when facing such issues. After collecting the 394 participants responses, the results reveal that the contractor should reject to accelerate the work progress until gaining the compensation entitlement as a result of employ-er-caused delays, taking the risk of falling into the misery of liquidated damages. Also, the re-sults illustrate the contractors entitlements and project decisions when facing such problematic concerns. Different from previous papers, the findings of this paper propose a standard way of thinking towards these problematic issues.

Quantifying the cascading effects of passenger delays

Delays in transport networks has adverse implications for infrastructure and service managers as well as travellers. While it is widely acknowledged that delays occurring across the transport networks may be related, there are is lack of knowledge on the underlying properties of these relations and means for quantifying them. To this end, we develop a network-wide data-driven delay analysis method. First, we construct a Bayesian network to represent the relations between delays associated with different transport network elements and assess the reliability of critical infrastructure elements. Second, we propose a series of original metrics denominated informativity indicators for quantifying the spatial extent of the delays observed based on the Bayesian network obtained. The proposed approach is applied to the Washington DC metro network. Time-dependent passenger waiting and transferring delays inferred over more than a year from smartcard data are utilized as input to the Bayesian network. Our findings indicate that passenger delays at few selected stations are directly informative of delays occurring at many other stations. We also examine the relation between the proposed informativity metrics and the topological properties of metro stations, concluding that the latter have a limited value in approximating network-wide delay correlations.

Information flow perception modeling and optimization of Internet of Things for cloud services

IoT (Internet of Things) information flow perception is the foundation of the IoT architecture and plays an important role. Providing cloud services on demand is one of the key issues and core features of cloud services in the IoT information flow perception. Firstly, we study the mixed logic dynamics (MLD) modeling method of IoT information flow awareness, and use IoT sensor nodes, controlled nodes, and coordination nodes to describe system application scenarios, and use automata for internal information transmission. Secondly, an open queuing method based on large-scale information flow perception modeling and network delay analysis method is proposed. By analyzing the end-to-end delay of the node path and the average delay analysis of the whole queuing network, the open queuing is obtained. Aiming at the characteristics of distributed data of information flow perception in the IoT, a priority-based queuing network is proposed to model and analyze the aggregation nodes based on embedded multi-core SoC(System on Chip), which greatly improves the performance of embedded multi-core SoC.

Integrated Probabilistic Delay Analysis Method to Estimate Expected Outcome of Construction Delay Disputes

AbstractDelays are almost inevitable in construction projects. They can have a devastating effects on the project. Therefore, proper analysis of delays and apportionment of liability is of utmost i...

Delay analysis in construction projects with no updated work schedules

PurposeIn smaller projects with limited resources, schedule updates are often not performed. In these situations, traditional delay analysis methods cannot be used as they all require updated schedules. The objective of this study is to develop a model that performs delay analysis by using only an as-planned schedule and the expense records kept on site.Design/methodology/approachThis study starts out by developing an approach that estimates activity duration ranges in a network schedule by using as-planned and as-built s-curves. Monte Carlo simulation is performed to generate candidate as-built schedules using these activity duration ranges. If necessary, the duration ranges are refined by a follow-up procedure that systematically relaxes the ranges and develops new as-built schedules. The candidate schedule that has the closest s-curve to the actual s-curve is considered to be the most realistic as-built schedule. Finally, the as-planned vs. as-built delay analysis method is performed to determine which activity(ies) caused project delay. This process is automated using Matlab. A test case is used to demonstrate that the proposed automated method can work well.FindingsThe automated process developed in this study has the capability to develop activity duration ranges, perform Monte Carlo simulation, generate a large number of candidate as-built schedules, build s-curves for each of the candidate schedules and identify the most realistic one that has an s-curve that is closest to the actual as-built s-curve. The test case confirmed that the proposed automated system works well as it resulted in an as-built schedule that has an s-curve that is identical to the actual as-built s-curve. To develop an as-built schedule using this method is a reasonable way to make a case in or out of a court of law.Research limitations/implicationsPractitioners specifying activity ranges to perform Monte Carlo simulation can be characterized as subjective and perhaps arbitrary. To minimize the effects of this limitation, this study proposes a method that determines duration ranges by comparing as-built and as-planned cash-flows, and then by systematically modifying the search space. Another limitation is the assumption that the precedence logic in the as-planned network remains the same throughout construction. Since updated schedules are not available in the scenario considered in this study, and since in small projects the logic relationships are fairly stable over the short project duration, the assumption of a stable logic throughout construction may be reasonable, but this issue needs to be explored further in future research.Practical implicationsDelays are common in construction projects regardless of the size of the project. The critical path method (CPM) schedules of many smaller projects, especially in developing countries, are not updated during construction. In case updated schedules are not available, the method presented in this paper represents an automated, practical and easy-to-use tool that allows parties to a contract to perform delay analysis with only an as-planned schedule and the expense logs kept on site.Originality/valueSince an as-built schedule cannot be built without updated schedules, and since the absence of an as-built schedule precludes the use of any delay analysis method that is acceptable in courts of law, using the method presented in this paper may very well be the only solution to the problem.

A Modified Double Subculture Method for the Two-Mode Injuries Evaluation in a Stressed Fungal Spore Population.

In order to evaluate injury of a stressed fungal spore population, a modification of formerly presented double subculture method, which consists of both the conventional plate count method and the growth delay analysis method, was proposed. In this method, an apparent logarithmic growth kinetics was assumed and the previous kinetic model was improved to be able to estimate injured subpopulations in two different modes containing early occurring growth-independent and late occurring growth-dependent injuries, called the λ and μ injuries, respectively. Based on the kinetic theory developed here, this novel method was applied to heat-treated conidia of Cladosporium cladosporioides and these two mode injuries were evaluated.

Method for delaying responsibility allocation of power grid infrastructure projects considering logical relationship between engineering processes

Delaying responsibility allocation is one of the important contents in the construction management of power grid infrastructure projects. Due to the large investment in power grid infrastructure projects, long construction period and complicated operation procedures, many delays occurred during the construction process. Based on this, combined with the theory of time difference theory, this paper proposes a delay analysis method that considers the logical relationship between engineering processes. Secondly, the route time difference theorem is proposed, and the calculation steps and rules of the delay analysis method considering the logical relationship between engineering processes are given. Finally, the substation main structure construction project is selected as an example analysis, and compared with other methods, which effectively proved that the validity and feasibility of the proposed delay analysis method. The method of delay responsibility allocation proposed in this paper also provides ideas and directions for the subsequent research on delay assignment of similar construction projects.

Assimilation Impact of Different GPS Analysis Methods on Precipitation Forecast: A Heavy Rainfall Case Study of Kani City, Gifu Prefecture on July 15, 2010

In this study, we examined variations in predicted precipitable water produced from different Global Positioning System (GPS) zenith delay methods, and assessed the corresponding difference in predicted rainfall after assimilating the obtained precipitable water data. Precipitable water data estimated from the GPS and three-dimensional horizontal wind velocity field derived from the X-band dual polarimetric radar were assimilated in CReSS and rainfall forecast experiments were conducted for the heavy rainfall system in Kani City, Gifu Prefecture on July 15, 2010. In the GPS analysis, a method to simultaneously estimate coordinates and zenith delay, i.e., the simultaneous estimation method, and a method to successively estimate coordinates and zenith delay, i.e., the successive estimation method, were used to estimate precipitable water. The differences generated from using predicted orbit data provided in pseudo-real time from the International GNSS (Global Navigation Satellite System) Service for geodynamics (IGS) versus precise orbit data released after a 10-day delay were examined. The change in precipitable water due to varying the analysis methods was larger than that due to the type of satellite orbit information. In the rainfall forecast experiments, those using the successive estimation method results had a better precision than those using the simultaneous estimation method results. Both methods that included data assimilation had higher rainfall forecast precisions than the forecast precision without precipitable water assimilation. Water vapor obtained from GPS analysis is accepted as important in rainfall forecasting, but the present study showed additional improvements can be attained from incorporating a zenith delay analysis method.

Theoretical development of stochastic delay analysis and forecast method

Schedule delay analysis and claim management for construction projects have received much attention recently due to an increasing number of construction disputes. Most of the available delay analysis methods employ a deterministic approach that uses deterministic activity duration in as-planned schedules for schedule comparison. However, the duration of construction projects is naturally uncertain. Based on a mathematical-model delay analysis method, this study proposes an innovative approach, the Stochastic Delay Analysis and Forecast method (the SDAF method), which combines probabilistic activity duration and systematic delay analysis procedures to predict the contribution of a single activity’s delay and its probability to cause overall project delay. This paper proposes a methodology and examines its results by means of a simulated case. Although this study has simplified practical problems, preliminary study results are valuable and form a basis for further research. Namely, these study results provide not only a stochastic delay analysis and forecast method but also a fundamental basis for developing advanced schedule delay analysis methodology to help in solving complicated schedule delay problems in construction projects.

Criticality index delay analysis method based on float allocation

How to allocate float and how to apportion delay responsibility are two central issues in delay analysis. To solve these two issues, many scholars had proposed various methods. The primary objective of this study is to construct a new delay analysis method based on the float allocation. In terms of float allocation, the length of each activity time has been taken as the basis for apportioning floats in most past methods. However, an activity with a longer duration may not directly mean more delayed risk inherent in that activity. When analyzing the attribution of delay responsibility, past methods did not consider certain problems associated with weight of severity, namely responsibility assignment on critical and noncritical delays. To resolve these two issues, this paper proposes a new method, referred to as the criticality index delay analysis method based on float allocation (CIDAMFA). In this paper, the rationale and algorithm of CIDAMFA will be introduced and published case data will be used to exemplify the proposed method of CIDAMFA. Using the proposed method, the floats can be allocated more efficiently. Meanwhile, the problem of comparative severity among critical and noncritical delays is resolved.

Incorporating lost productivity calculation into delay analysis for construction projects

Schedule delays commonly occur in construction projects and often result in delay claims. Several studies have proposed different schedule delay analysis methodologies. By using as-planned and as-built schedules, most previous studies have concentrated on calculating the impact of identified delay events on project duration but have neglected to connect impact calculation from detailed delay evidence in their analyses. Lost productivity, which is a primary cause of schedule delays, entails the completion of work at less than the planned rate of production; it is usually experienced by contractors. To solve analysis problem of schedule delays associated with lost productivity, this study proposes a delay analysis method (the LOPE method) that integrates a lost productivity calculation approach and a well-known schedule delay analysis method, the collapsed as-built method. As demonstrated through a simplified case study, the proposed method is beneficial for calculating the impacts of schedule delays caused by lost productivity.