Factors Affecting Ship Design and Construction Lead Time and Cost

2005 ◽  
Vol 21 (03) ◽  
pp. 186-194
Author(s):  
Howard Moyst ◽  
Biman Das
Keyword(s):  
Design Process ◽  
Lead Time ◽  
Ship Design ◽  
Start Time ◽  
Design Quality ◽  
Improve Design ◽  
Design Changes ◽  
The Impact ◽  
Design And Construction

This paper reviews a ship design and construction case study in the context of the published literature on the design process and its impact on construction. The objective was to explore the factors that impact design and construction lead time and cost. Design and construction managers constantly experience pressure to accelerate the construction start time in an environment characteristic of frequent design changes and rework. Often the construction of the first ships of a series will aggressively overlap the design phase. This investigation assessed a case study that illustrated that as the degree of overlap between design and construction increases, design changes increased ship construction costs and duration. This negates the advantage of trying to reduce lead time by overlapping phases. Before strategies of overlapping are utilized, shipbuilders need to better understand the details of the design process and its integration with other functions to improve design quality and reduce the impact of design changes on manufacturing and construction. It is recommended that when overlapping strategies are considered, design changes and their impact on construction be factored into the decision. A better strategy would be to eliminate design quality issues and design and construction rework.

Reduction of Impact Noise at the Design Stage: A Specific Case Study

1972 ◽  
Vol 186 (1) ◽  
pp. 391-399
Author(s):  
M. A. Salter ◽  
B. Downs ◽  
G. R. Wray
Keyword(s):  
Experimental Approach ◽  
Design Stage ◽  
Experimental Investigations ◽  
Theoretical Treatment ◽  
Impact Noise ◽  
Design Changes ◽  
Machine Cycle ◽  
Mechanism Of Impact ◽  
The Impact

A case study is made on the tack driving assembly of a boot and shoe lasting machine, and relates to the impact noise occurring during part of the machine cycle. Much of the noise is radiated due to vibrations at several frequencies of the tack driver lifting lever, which is excited by the direct application of impacts during the tack driving process. An experimental approach in applying noise reduction principles to various components of the assembly has been preferred to a more complex theoretical treatment, since the identification of the mechanism of impact noise generation and its subsequent abatement is directly relevant to most machine designers faced with the possibility of impact noise problems in other types of machinery. Small design changes, based on the knowledge gained from the experimental investigations, have resulted in noise reductions from 10 to 14 dB being achieved.

Exploring mass customization and textile application in medical products: re-designing scoliosis brace for shorter production lead time and better quality of life

2020 ◽  
Vol 90 (19-20) ◽  
pp. 2304-2321
Author(s):  
Olivia Ho-Yi Fung ◽  
Joanne Yip ◽  
Mei-Chun Cheung ◽  
Kit-Lun Yick ◽  
Kenny Yat-Hong Kwan ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Patient Compliance ◽  
Mass Customization ◽  
Lead Time ◽  
Interface Pressure ◽  
Negative Impacts ◽  
Exerted Pressure ◽  
The Impact

Bracing is the most common non-operative treatment option for patients with adolescent idiopathic scoliosis (AIS). However, existing brace designs have deficiencies, including a long production lead time and low patient compliance caused by the negative impacts of bracing on quality of life (QoL). The aim of this study was to address these problems by developing a new textile-based scoliosis brace in accordance with the biomechanics used in the existing braces for spinal correction. A case study of interface pressure had been carried out to determine the optimum combination of pads to be used in the proposed brace to correct a scoliotic spine. AIS patients who were undergoing hard brace treatment were recruited to complete a questionnaire (BrQ) on hard braces and on the proposed brace. The BrQ scores of the two types of braces were compared to assess their respective impacts on the QoL. The findings show that the proposed brace can address the issue of patient compliance by reducing the impact of bracing on QoL, and shorten the production lead time through incorporation of the mass customization concept into the design. Similar to most of the commonly-used scoliosis braces, the selected combination of pads used in the proposed brace for spinal correction shows a sufficient amount of exerted pressure and a similar function of active spinal correction.

Flexible Multistage Bayesian Models for Use in Conceptual Design

2002 ◽  
Author(s):  
Jorge E. Pacheco ◽  
Cristina H. Amon ◽  
Susan Finger
Keyword(s):  
Conceptual Design ◽  
Design Process ◽  
Computational Models ◽  
Analytical Form ◽  
Surrogate Models ◽  
Improve Design ◽  
Process Visualization ◽  
Rigorous Framework ◽  
Main Effects

During conceptual design, designers need tools to help improve design decisions and reduce design times. We are working to develop techniques to create Bayesian surrogate models that respond to designers’ needs during conceptual stages of the design process. Bayesian surrogate models give analytical form to the overall performance of a system and can evolve along with the design. Bayesian surrogate models provide a mathematically rigorous framework in which computational models can be updated based on previous outcomes. In this paper, we present techniques that allow the addition or suppression of parameters without discarding previously obtained information. We also present a case study that illustrates how a surrogate model is constructed in stages when parameters are added or suppressed during the design process. Visualization tools, such as plots of the main effects of parameters, can be derived from surrogate models. These tools can be used to provide knowledge about the parameters that influence the design. Finally, a design problem is used to illustrate how Bayesian surrogate models can inform the designer about tradeoffs that would not be apparent from simulation data alone.

Computer-aided design versus sketching: An exploratory case study

2012 ◽  
Vol 26 (3) ◽  
pp. 317-335 ◽  
Author(s):  
David Veisz ◽  
Essam Z. Namouz ◽  
Shraddha Joshi ◽  
Joshua D Summers
Keyword(s):  
Design Process ◽  
Computer Aided Design ◽  
Mechanical Engineering ◽  
Computer Assisted ◽  
Cad Tools ◽  
Design Project ◽  
Computer Aided ◽  
Aided Design ◽  
The Impact

AbstractThis paper presents a preliminary comparison between the role of computer-aided design (CAD) and sketching in engineering through a case study of a senior design project and interviews with industry and academia. The design team consisted of four senior level mechanical engineering students each with less than 1 year of professional experience are observed while completing an industry sponsored mechanical engineering capstone design project across a 17 week semester. Factors investigated include what CAD tools are used, when in the design process they are implemented, the justification for their use from the students' perspectives, the actual knowledge gained from their use, the impact on the final designed artifact, and the contributions of any sketches generated. At each design step, comparisons are made between CAD and sketching. The students implemented CAD tools at the onset of the project, generally failing to realize gains in design efficiency or effectiveness in the early conceptual phases of the design process. As the design became more concrete, the team was able to recognize clear gains in both efficiency and effectiveness through the use of computer assisted design programs. This study is augmented by interviews with novice and experienced industry users and academic instructors to align the trends observed in the case study with industry practice and educational emphasis. A disconnect in the perceived capability of CAD tools was found between novice and experienced user groups. Opinions on the importance of sketching skills differed between novice educators and novice industry professionals, suggesting that there is a change of opinion as to the importance of sketching formed when recent graduates transition from academia to industry. The results suggest that there is a need to emphasize the importance of sketching and a deeper understanding as to the true utility of CAD tools at each stage of the design process.

Assessing design process in engineering consultancy firms using lean principles

SIMULATION ◽  
2012 ◽  
Vol 88 (12) ◽  
pp. 1522-1536 ◽  
Author(s):  
M Marzouk ◽  
I Bakry ◽  
M El-Said
Keyword(s):  
Design Process ◽  
Comprehensive Model ◽  
Output Analysis ◽  
Lean Principles ◽  
Proposed Model ◽  
Client Request ◽  
Using Data ◽  
Consultancy Firm ◽  
The Impact

The aim of this research is to provide a tool for assessing the impact of applying lean principles to the design process at construction consultancy firms. Through several interviews, a comprehensive model was built to simulate the design process, using data from a leading consultancy firm in Egypt. The model contains the main processes and activities that form different phases of the design process and depicts the interconnectivity of processes and activities needed to create a complete design package upon client request. The research describes how the five main lean principles are integrated in the model. A case study is considered to demonstrate the effect of using the proposed model on the design process and to illustrate how the design process performs differently when lean principles are introduced. Case study output analysis reveals 40% improvement in the lean process performance measured in terms of activity utilization rates.

Improving the performance of a diesel engine by changing injectors characteristics after reduction on the compression ratio

2021 ◽  
Vol 15 (2) ◽  
pp. 8153-8168
Author(s):  
Saeed Chamehsara ◽  
Mohammadreza Karami
Keyword(s):  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Engine Performance ◽  
Combustion Engines ◽  
Fuel Injector ◽  
Start Time ◽  
Performance And Emissions ◽  
Nozzle Hole ◽  
The Impact

In order to repair internal combustion engines, sometimes it is necessary to replace the components of these engines with each other. Therefore changes in engine performance are inevitable in these conditions. In the present study, by changing the coneccting rod and the crank of the OM457 turbo diesel-fueled engine with the OM444, it was observed that the performance of the engine decreases. Numerical simulations have been carried out to study the Possible ways to mitigate this reduction. One way to achieve this goal is to change the fuel injector’s characteristics such as, fuel injector’s nozzle hole diameter, number of nozzle holes, and start time of fuel injection. In this study, the impact of these parameters on the performance and emissions of these engines were analyzed. Another scenario is an increase in inlet fuel and air by the same amount. The results indicate that By reducing the diameter of fuel injector holes and hole numbers, the performance of the engine was increased. on the other hand, the NOx emissions were increased while the amount of soot emission decreased. The same results were concluded by retarding the start time of injection. Subsequently, a case study of changing fuel injector parameters for mitigation of decreased performance was performed. These parameters were simultaneously applied, and results were compared. The performance of the engine with improved injector’s characteristics was close to the main OM457. Similar results were obtained by increasing the amount of inlet air and fuel.

The Fit Between Spatial Configuration and Idealized Flows: Mapping Flows in Surgical Facilities as Part of Case Study Visits

2020 ◽  
pp. 193758672092835
Author(s):  
Herminia Machry ◽  
Anjali Joseph ◽  
Deborah Wingler
Keyword(s):  
Design Process ◽  
Spatial Configuration ◽  
Healthcare Services ◽  
Design Teams ◽  
Flow Mapping ◽  
Healthcare Facilities ◽  
Mapping Tool ◽  
Mapping Approach ◽  
The Impact

Purpose: This study proposes a flow mapping approach for surgical facilities that can be implemented by design teams as a component of case study tours. Background: The provision of healthcare services involves simultaneous and closely coupled flows of people, objects, and information, and the efficiency of these flows is influenced by the spatial configuration of the buildings where these services are housed. Many architecture firms conduct case study tours to inform their design process. However, these tours often lack a structured way of documenting different flows and interpreting observations. A structured approach is needed during the design process to understand the impact of spatial configuration on healthcare flows. Method: Site tours were conducted at four surgery centers to develop and test an evidence-based flow mapping approach. Idealized flows within surgical facilities were first identified from the literature, followed by the development of a data collection tool aimed at documenting these flows in each case study through a pre-assessment questionnaire, a physical assessment, and interviews with staff. Results: The flow mapping tool kit was effective in allowing the design team to systematically understand the physical configuration of surgical flows across case studies. The tool also allowed the team to identify spatial configuration characteristics acting as barriers and facilitators to idealized flows. Conclusions: The flow mapping approach was able to provide structure for conducting these short tours more effectively via observations and staff inquiry, enabling design teams to draw more meaningful conclusions from case study tours and conduct comparisons between healthcare facilities visited.

Construction productivity assessment on Brock Commons Tallwood House

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohamed Kasbar ◽  
Sheryl Staub-French ◽  
Angelique Pilon ◽  
Erik Poirier ◽  
Zahra Teshnizi ◽  
...  
Keyword(s):  
Innovation Process ◽  
Lessons Learned ◽  
Longitudinal Case Study ◽  
Virtual Design ◽  
Content Type ◽  
Construction Productivity ◽  
Mass Timber ◽  
The Impact ◽  
Design And Construction

Purpose The purpose of this paper is to improve the understanding of the impact of mass timber construction methods on construction performance through the successful delivery of the first-of-a-kind tall wood building, Brock Commons Tallwood House (Tallwood House). This paper is one of a set of papers examining the project; companion papers describe innovations used during the mass timber design and construction processes. Design/methodology/approach A mixed-method, longitudinal case study approach was used in this research project to investigate and document the Tallwood House project. Quantitative data were collected to perform the following analysis: hook time, the variability of productivity and schedule reliability. Members of the research team observed construction progress, meetings and decision-making, conducted periodic interviews and reviewed project artifacts. Findings The research presented in this paper is the culmination of a longitudinal study aimed at studying the innovation process on a project where radical innovations of structural systems were developed. Prefabrication, combined with the use of a virtual design and construction (VDC) model for planning and fabrication and early collaboration with trades, construction managers and consultants, increased the labor productivity of the on-site erection of the mass timber structural components and envelope panels and expedited the construction schedule. Originality/value This paper details an in-depth investigation into the construction productivity for a unique building project and lessons learned. The case study chosen is the construction of Tallwood House at the University of British Columbia. Tallwood House was the tallest mass-timber hybrid building in the world at the time of its construction.

A Linear Programming Approach to Optimization of Ship Design and Construction Phases

2008 ◽  
Vol 24 (01) ◽  
pp. 1-6
Author(s):  
Howard Moyst ◽  
Biman Das
Keyword(s):  
Linear Programming ◽  
Labor Cost ◽  
Ship Design ◽  
Programming Approach ◽  
Actual Case ◽  
Study Results ◽  
Lp Model ◽  
Degree Of Overlap ◽  
Design And Construction

Labor cost savings can be obtained by considering the effect of design rework on the degree of overlap of the ship design and construction phases. Based on data from a shipbuilding case study, a linear programming (LP) model was developed to investigate the optimum overlap of the design and construction phases. Two scenarios were modeled. The case study's start-up period, which involved design and the construction of four ships, and a hypothetical small batch program to determine the degree of overlap and total hours required for a new shipbuilding program. In each scenario, the LP model found the optimum overlap period for design and construction and the associated total hours. In the first scenario, the analysis demonstrates that by reducing the amount of overlap between the design and construction phases, a reduction in construction direct labor hours can be achieved while obtaining the overall duration and scheduled completion times. In the second case, the analysis recommends a zero overlap policy between the design and construction phases to minimize total hours while achieving the overall schedule duration. When compared with the actual case study results, the zero overlap policy estimates an $8 million saving. The analysis supports the policy to complete design activities with construction-dependency relationships before starting construction.

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