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“Economics is a Serious Subject.” Edwin Cannan.

An S-curve is an essential project-management tool. However, it is difficult to adjust S-curve to deal with a force majeure event. The present study develops four valuable adjustment approaches, designed to achieve a compromise between the views of the client and contractor. These can be used to control projects after a force majeure event.

The present study develops four adjustment approaches, which can be used to achieve a compromise between the views of the client and those of the contractor when controlling projects after a force majeure. To determine the S-curves during a force majeure event, two approaches can be selected: BCWS (budgeted cost of scheduled work)-base approach, or BCWP (budgeted cost of work performed)-base approach. To determine the rest of S-curves after a force majeure event, two approaches can be considered: maintaining the original curve of the remaining BCWS, or allocating the original curve of the remaining BCWS. Based on the validation of three empirical cases, drawn from a professional project-management website, this study confirms the feasibility of four proposed empirical approaches and a selection procedure for S-curve adjustment.

The S-curve-adjustment approaches presented here can be used to deal with cases that are ahead of, on and behind schedule. Using the proposed approaches and selection procedure, contractors can easily revise S-curves and control projects more effectively. To deal with a force majeure event, such as COVID-19, they are strongly advised to adopt the approaches labeled SA-A1 (to adjust the S-curve based on the extension ratio multiplied by the difference in progress during the force majeure) and SA-B1 (to maintain the original curve of the remaining BCWS) for the A/E and E/F curves, respectively.

The proposed approaches can be used in cases of continuous construction during force majeure events. If construction work is totally suspended during such an event, it will be necessary to fine-tune the proposed approaches.

Previous studies have used case-oriented or mathematical-simulation approaches to forecast S-curves. The present study proposes simple approaches that allow the client and contractor to adjust the S-curve easily after a force majeure event. These approaches can be used to adjust work and project-completion targets within an extended duration. Selecting the right S-curve adjustment approach can help to control the remainder of the project, reducing the possibility of delay claims.

Several cash flow forecasting models have been developed for use by the contractor at the tendering stage. The majority of these models have been based on the standard S‐curve. The accuracy of these models depends on the accuracy of the standard S‐curve used. Many researchers have attempted to develop standard S‐curves using past projects. These projects were primarily classified in terms of broad‐based categories (e.g. commercial buildings). The results of past research have demonstrated that cumulative value/cost curves vary significantly. In the present paper, a more specific type of building was selected (food retail stores). Historical data for 20 projects was collected and analysed for the feasibility of developing a more accurate standard S‐curve. The results demonstrate that an accurate standard S‐curve was not achieved even when projects were further classified into more detailed groups (i.e. different sizes of superstores).

Waverider has high lift to drag ratio and will be an idea aerodynamic configuration for hypersonic vehicles. But a structure permitting aerodynamic like waverider is still difficult to generate under airframe’s geometric constrains using traditional waverider design methods. And furthermore, traditional waverider’s aerodynamic compression ability cannot be easily adjusted to satisfy the inlet entrance requirements for hypersonic air-breathing vehicles. The purpose of this paper is to present a new method named osculating general curved cone (OCC) method aimed to improve the shortcomings of traditional waveriders.

A basic curved cone is, first, designed by the method of characteristics. Then the waverider’s inlet captured curve and front captured tube are defined in the waverider’s exit plane. Osculating planes are generated along the inlet captured curve and the designed curved cone is transformed to the osculating planes. Streamlines are traced in the transformed curved cone flow field. Combining all streamlines which have been obtained, OCC waverider’s compression surface is generated. Waverider’s upper surface uses the free stream surface.

It is found that OCC waverider has good volumetric characteristics and good flow compression abilities compared with the traditional osculating cone (OC) waverider. The volume of OCC waverider is 25 per cent larger than OC waverider at the same design condition. Furthermore, OCC waverider can compress incoming flow to required flow conditions with high total pressure recovery in the waverider’s exit plane. The flow uniformity in the waverider exit plane is quite well.

The analyzed results show that the OCC waverider can be a practical high performance airframe/forebody for hypersonic vehicles. Furthermore, this novel waverider design method can be used to design a structure permitting aerodynamic like waverider for a practical hypersonic vehicle.

The paper puts forward a novel waverider design method which can improve the waverider’s volumetric characteristics and compression abilities compared with the traditional waverider design methods. This novel design approach can extend the waverider’s applications for designing hypersonic vehicles.

Since the introduction of the concepts of the J‐ and S‐curves, many researchers have tried to verify their validity empirically. This paper aims to review the related papers and to offer direction for future research.

This is a review paper. As such, no method is employed here. Rather, the methodologies used by others to test the J‐ and S‐curves are explained and reviewed.

No new findings are offered since this is a review paper.

The J‐ and S‐curves show whether currency depreciation worsens the trade balance first before improving it. Since the majority of studies are country‐specific, policymakers could benefit by learning whether currency depreciation will be effective in improving the trade balance.

This is a literature review paper and its originality is in terms of collecting the literature together and presenting it in one single paper.

The present essay re-examines the scope of Sraffa’s critique of Marshall’s supply curves that the former developed in his 1925 and 1926 articles showing that neoclassical supply curves derived from non-proportional returns are not robust both in the short and in the long run. After examining what a short-run and a long-run equilibrium means both for the original Sraffa’s articles and for Marshall’s pioneer contribution, the chapter discusses the common procedure in conventional economics to introduce the limitations to the growth of the firm. The argument of the chapter will be based on the 1920s articles as well as on the ‘Lectures on Advanced Theory of Value’ delivered in 1928–1931 by Sraffa at Cambridge University, now publicly available online by the Wren library, Trinity College, Cambridge. For short-run analysis, it must be assumed that the number of firms is fixed. This assumption entails serious problems with regards to the notions of competition and competitive behaviour. For long-run analysis, the sources of increasing costs are problems of management and control. However, this idea is untenable both on logical and empirical grounds. We argue that contemporary mainstream microeconomic treatment of costs and supply in the context of perfect competition still presents several problems. These problems, rather than being superficial, lie at the root of the supply and demand approach of value and distribution.

Failure of a critical reinforced concrete beam due to fatigue can have severe safety and production consequences, and preventative repair/replacement of such a beam is expensive. It would therefore be beneficial if repair/replacement can be done based on an accurately and conservatively predicted remaining useful life (RUL). The purpose of this paper is to develop such a model.

Condition-based maintenance is a maintenance approach that uses empirical/analytical models and a measurable condition to predict remaining useful life. The P-F curve (condition-life) is a useful tool that can aid in making these decisions. A model to create a P-F curve is developed using rebar fatigue test results (in the form of an S–N curve) and the Palmgren-Miner law of damage accumulation. A Monte Carlo simulation with statistical distributions is employed to provide confidence levels of RUL outputs.

An example of how the model can successfully be used in practice is shown in this paper, and a sensitivity study is performed leading to conclusions being drawn with regard to damage tolerant design considerations.

If a critical reinforced concrete beam fails due to fatigue can have serious consequences. This paper develops a model to help base repair/replacement decisions based on accurately and conservatively predicted RUL. Financial and safety benefits would be gained if this model would be used in practice.

Both the Product Life Cycle (PLC) and a new version, the Product Evolutionary Cycle (PEC), are more than just descriptive marketing tools based on historical sales data. Rather, they represent dynamic instruments to enable an entrepreneur‐or coporate manager‐to estimate market development. The S‐curve, the growth part of the PLC and the PEC, makes it possible for an entrepreneur to time capital requirements, labor force recruitment, promotional efforts, distribution channels, target markets, and pricing. In the case of new products, research can be utilized to construct an S‐curve in advance of an innovation's introduction in the market‐place. Such information is invaluable to an entrepreneur, since it serves as a guide to future market development.