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Business cycle theory is normally described as having evolved out of a previous tradition of writers focusing exclusively on crises. In this account, the turning point is seen as residing in Clément Juglar's contribution on commercial crises and their periodicity. It is well known that the champion of this view is Schumpeter, who propagated it on several occasions. The same author, however, pointed to a number of other writers who, before and at the same time as Juglar, stressed one or another of the aspects for which Juglar is credited primacy, including the recognition of periodicity and the identification of endogenous elements enabling the recognition of crises as a self-generating phenomenon. There is indeed a vast literature, both primary and secondary, relating to the debates on crises and fluctuations around the middle of the nineteenth century, from which it is apparent that Juglar's book Des Crises Commerciales et de leur Retour Périodique en France, en Angleterre et aux États-Unis (originally published in 1862 and very much revised and enlarged in 1889) did not come out of the blue but was one of the products of an intellectual climate inducing the thinking of crises not as unrelated events but as part of a more complex phenomenon consisting of recurring crises related to the development of the commercial world – an interpretation corroborated by the almost regular occurrence of crises at about 10-year intervals.

Increasing scarcity of natural resources and the adverse effects of unsustainable practices call for more and more efficient management strategies in the energy industry. The quality of the coke plays a significant role in the quality and durability of the output steel which is produced using the energy from the coal. This paper aims to investigate the dynamic coal blending problem under overall cost and coke quality constraints in the steel industry within a periodic cycle of operations.

Considering the variability of the natural properties over a periodic cycle, this study proposes a multi-period mixed-integer non-linear programming formulation to optimize the total blending costs while taking various coke quality constraints into account. Besides, this study applies factorial design to investigate about the significant effect of coal proportions as well as improvement into the overall cost of blending.

In this case study, utilizing real data from a coal blending facility in India, through a factorial design, the authors obtain optimal desirable levels of coal proportions and their criticality levels towards the total cost of blending (TCB) or objective function. This analysis reflects the role of the coke quality constraints in the objective function value while characterizing the price of sustainability for the case study among other critical insights.

Objective function (or TCB) includes basic coal cost, movement cost and environmental costs during the coal and coke processing at a coke-oven and blast furnace of steel industry. The price of sustainability provides managerial insights on that sacrifices the industry has to make in order to become more “sustainable”.

The occupational health risk associated with the production of prefabricated concrete components is often overlooked. This paper will use a damage assessment and cyclic mitigation (DACM) model to provide individualized exposure risk assessment and corresponding mitigation management measures for workers who are being exposed.

The DACM model is proposed based on the concept of life cycle assessment (LCA). The model uses Monte-Carlo simulation for uncertainty risk assessment, followed by quantitative damage assessment using disability-adjusted life year (DALY). Lastly, sensitivity analysis is used to identify the parameters with the greatest impact on health risks.

The results show that the dust concentration is centered around the mean, and the fitting results are close to normal distribution, so the mean value can be used to carry out the calculation of risk. However, calculations using the DACM model revealed that there are still some work areas at risk. DALY damage is most severe in concrete production area. Meanwhile, the inhalation rate (IR), exposure duration (ED), exposure frequency (EF) and average exposure time (AT) showed greater impacts based on the sensitivity analysis.

Based on the comparison, the DACM model can determine that the potential occupational health risk of prefabricated concrete component (PC) factory and the risk is less than that of on-site construction. It synthesizes field research and simulation to form the entire assessment process into a case-base system with the depth of the cycle, which allows the model to be continuously adjusted to reduce the occupational health damage caused by production pollution exposure.

The purpose of this numerical study is to analyse the character of transition from laminar to chaotic convection in a fluid layer bounded by no‐slip walls in two space dimensions for varying aspect ratio odd‐shaped enclosures consisting of two rectangular chambers, with a linking horizontal enclosure. For a medium Prandtl number fluid (Pr=7), the numerical solution of two‐dimensional Navier‐Stokes momentum and energy equations with Bousinessq approximation has been carried out. It has been found that there are finite Rayleigh numbers Ra₁, Ra₂ and Ra₃ for the onset of single, two and multiple frequency oscillatory motion at different spatial locations in the enclosure. As Ra is further increased period doubling is observed. The onset of strong chaos appears when Ra=Ra₃. This system does not revert to steady state convection at high Ra as observed by other researchers for the case of Rayleigh‐Benard convection. Moreover, the period doubling transition process is consistent with the scenario of Ruelle, Takens and Newhouse. As Ra increases, the power spectrum, and time series of various dynamical variable signals, etc. all show an increasing degree of characteristics of chaos.

When confronted with issues dealing with first and second order cybernetics, it seems that the manner of defining the former has been somewhat caricatured. The second appears to sometimes give rise to conclusions which are almost opposite to those of Wiener by questioning the possibility of a control for a system. We find in Wiener’s research a prefiguration of the autonomy concept, which, in our opinion, could bring an explanation – and a solution – in cases where control elicits some perverse effect; an acceptance of positive feedback if it serves a desired purpose; the central importance held for him by ergodic theory that we use in an addendum on imbalanced strange attractors control; the idea of a knowledge which may be the fruit of the control; an interest for logical paradoxes he put in relation to communication in nervous system; and already the notion of dialogue in the core of the relation man/man or man/machine. Of course, Wiener did not accord an equal development to all his insights, but we have not yet finished scrutinizing his writings. First and second order cybernetics perhaps form an agonistic/antagonistic couple of which neither element could overshadow the other.

With the popularity of electronic commerce, many organizations are facing unprecedented security challenges. Security techniques and management tools have caught a lot of attention from both academia and practitioners. However, there is lacking a theoretical framework for information security management. This paper attempts to integrate security policy theory, risk management theory, control and auditing theory, management system theory and contingency theory in order to build a comprehensive theory of information security management (ISM). This paper suggests that an integrated system theory is useful for understanding information security management, explaining information security management strategies, and predicting management outcomes. This theory may lay a solid theoretical foundation for further empirical research and application.

Many scholars have noted that, since at least 1790, U.K. economic fluctuations have seemed to reach major peaks every 7–10 years. Keynes (1936, ch.18) used the elements of his theory to explain non‐periodic economic fluctuations. His explanation of periodic fluctuations, i.e. cycles, appears in Chapter 22 of the General Theory. As is well known, he believed that fluctuations in “animal spirits” (that were often only loosely connected with the cost and the real rate of return on capital) led to oscillations in investment which, combined with the durability of capital goods, caused the duration of modern major cycles; fluctuations in liquidity preference and the propensity to consume played lesser roles. Bowing to Jevons (1964), Keynes also noted that unstable agricultural inventories could have been a source of waves in the early 19th Century when agriculture was relatively more important in the U.K. But Keynes did not demonstrate just how his investment theory implied a definite cycle period, because he did not merge his multiplier with the accelerator principle to provide an endogenous explanation of periodic turning points in output. Consequently, as Hicks (1950, p. l) notes, Keynes did not demonstrate how investment and income could peak every 7–10 years; his was really a theory of nonperiodic waves.

This paper aims to investigate the singular Hopf bifurcation and mixed mode oscillations (MMOs) in the perturbed Bonhoeffer-van der Pol (BVP) circuit. There is a singular periodic orbit constructed by the switching between the stable focus and large amplitude relaxation cycles. Using a generalized fast/slow analysis, the authors show the generation mechanism of two distinct kinds of MMOs.

The parametric modulation can be used to generate complicated dynamics. The BVP circuit is constructed as an example for second-order differential equation with periodic perturbation. Then the authors draw the bifurcation parameter diagram in terms of a containing two attractive regions, i.e. the stable relaxation cycle and the stable focus. The transition mechanism and characteristic features are investigated intensively by one-fast/two-slow analysis combined with bifurcation theory.

Periodic perturbation can suppress nonlinear circuit dynamic to a singular periodic orbit. The combination of these small oscillations with the large amplitude oscillations that occur due to canard cycles yields such MMOs. The results connect the theory of the singular Hopf bifurcation enabling easier calculations of where the oscillations occur.

By treating the perturbation as the second slow variable, the authors obtain that the MMOs are due to the canards in a supercritical case or in a subcritical case. This study can reveal the transition mechanism for multi-time scale characteristics in perturbed circuit. The information gained from such results can be extended to periodically perturbed circuits.

The purpose of this paper is to survey literature on macroeconomic nonlinear dynamics.

The paper identifies five influential types of models where the possible generation of endogenous cycles and chaotic motion arises. First, the frameworks that make use of the one‐hump logistic type equation; second, the models inspired on the growth literature of the 1940s; third, intertemporal utility maximization problems with increasing returns; fourth, models that can be represented as piecewise dynamic maps; and, fifth, bounded rationality – heterogeneous expectations setups.

The attention will be mainly focused on the theme of business cycles; an interpretation of the deterministic real business cycle model with increasing returns is proposed and a graphical analysis of the underlying system shows that strange attractors are observable for specific sets of parameter values.

The study of endogenous cycles in macroeconomic literature has important implications for policy: if fluctuations are due to deterministic reasons this may imply that by manipulating policy parameters governments may be able to change the qualitative nature of the economy's dynamics.

The paper gives a comprehensive view of nonlinear dynamics in macroeconomics. It shows that various relevant subjects might be addressed in this kind of models, e.g. economic growth, asset pricing, business cycles, consumption decisions, among others.