The evaluation of Istanbul airspace design from the perspective of complexity and safety

The approach, descent, and climb phases of flights in terminal maneuvering areas (TMAs) are some of the critical parts of a flight in which more than half of accidents happen. For an ANSP (Air Navigation Service Provider), to fulfill the responsibility with a high-quality service degree while maintaining safety, these difficult areas should be designed carefully and equipped with the most efficient procedures. Point merge system (PMS), which is defined as a systemized method for sequencing arrival flows, is launched in Istanbul's new TMA (LTFM TMA) being designed by DHMI (Devlet Hava Meydanları Isletmesi) to improve safety and efficiency. In this paper, the airspace complexity is based on adjusted density and structural index, and safety indicators. To investigate the effects of the radical changes made in re-organized LTFM TMA on the safety issue in comparison with the previous terminal maneuvering area, LTBA TMA, six months' data consisting of 75215 arrival and departure flights are used. Results reflect that the LTFM TMA, one of the world's busiest terminal airspaces, has statistically significantly lower scores in terms of conflict numbers per aircraft, complexity metrics, adjusted density, the hour of interactions, and flight hours than LTBA TMA. Lastly, there exists no longer a significant relationship between conflict types and complexity after launching the new design and structure.     

Moral hazard,debt overhang and capital structure

This paper investigates the impact of managerial moral hazard on the debt overhang of a firm by constructing a contingent claims model in which the manager faces costly effort. Using a calibrated capital structure model, we show that the costs of debt overhang become more serious in the presence of managerial moral hazard. Such costs even account for more than half of the total agency costs at a high level of cash flow. Moreover, in contrast to the results of Hackbarth and Mauer (2012), our model predicts a U-shaped relationship between the leverage ratio and investment opportunities of a firm, which is caused by managers’ moral hazard. Finally, by considering this moral hazard, we also show the coexistence of low leverage ratios and high credit spreads, which explains the phenomenon of “low debt levels and high credit spreads” observed in practice.     

离心式血液泵水力特性设计及其试验研究

借助商业软件NREC开展离心式血液泵的水力特性设计,其设计流量为5 L/min,设计转速为5000 r/min,得到离心叶轮和蜗壳的三维结构设计方案,并针对其全通道网格进行设计工况下三维流场的定常数值模拟研究.对其溶血性指标进行分析,发现离心式血液泵中95％ 区域切应力小于150 Pa,最大切应力小于500 Pa,满足人体对血液泵溶血性的要求.搭建离心式血液泵流量-压升特性试验测试平台,以质量分数为0.06％ 的黄原胶溶液为流动介质进行试验研究,试验结果显示在设计转速下的实际体积流量偏大于设计流量,整体压升在6550 Pa左右.     

Role of search for domain knowledge and architectural knowledge in alliance partner selection

Research Summary: The literature on technological alliances emphasizes that search for knowledge drives alliance formation. However, in conceptualizing technological knowledge, prior work on alliances has not made a distinction between domain knowledge—knowledge that firms possess in distinct technological domains—and architectural knowledge—knowledge that firms possess about how to combine elements from different technological domains. We argue that firms seek partners that are similar in domain knowledge to deepen their knowledge, and partners that are dissimilar in architectural knowledge to broaden their knowledge. Our results indicate that the likelihood of alliance formation increases when two firms are similar in domain knowledge and dissimilar in architectural knowledge. Further, our results show that these effects are positively moderated by the degree of decomposability of a firm's knowledge base. Managerial Summary: In dynamic environments, companies need to continually deepen and broaden their technological knowledge, and they often look for alliance partners who can provide them that knowledge. For knowledge deepening, companies are more likely to form alliances with those companies that have expertise in similar technological fields. For knowledge broadening, they are more likely to form alliances with those companies that have expertise in the same technological fields, but have different recipes for combining knowledge from those fields. Furthermore, a company with a modular knowledge base is more likely to seek a partner that has expertise in similar technological fields or whose recipes for combining knowledge from different technological fields are different from the recipes it has.     

Optimising flight connection times in airline bank structure through Simulated Annealing and Tabu Search algorithms

In hub and spoke airline networks, flight arrivals and departures generally have a bank structure to increase connections among spoke cities through a hub airport in order to provide cheaper service for higher volumes of air traffic. In this study, we introduce the airline bank optimisation problem with a novel mathematical model for improving flight connection times. The mathematical model aims to minimise the total connection times for transfer passengers and generates flight schedules regarding slot capacities in the hub airports. Since the problem is a combinatorial optimisation problem NP-hard and computational complexity increases rapidly for real-world problems, we employ the simulated annealing and the tabu search algorithms to achieve better solutions in a reasonable time. We generate sub-problems using real-world data and investigate the effectiveness of the algorithms. Finally, we present the results of a real case study of a Turkish airline company which has a hub airport connecting the flights between Middle Eastern and European cities.     

Some issues in blockchain for accounting and the supply chain,with an application of distributed databases to virtual organizations

This paper reviews some recent blockchain‐based applications for information capture, distribution and preservation. As part of that review, this paper examines two key concerns with current blockchain designs for accounting and supply chain transactions: data independence and multiple semantic models for the same information distribution problem. Blockchain applications typically integrate database, application and presentation tiers all in the same ledger. This results in a general inability to query information in the ledger and other concerns. Further, since most applications appear to be private blockchain applications, there is a concern of agents needing to accommodate multiple blockchains depending on who their trading partners are and what they request. Finally, this paper uses a distributed database to design a ‘blockchain‐like’ system for virtual organizations.     

Incorporating active adjustment into a financing based model of capital structure

The conventional partial adjustment model, which focuses on leverage evolution, has difficulty identifying deliberate capital structure adjustments as it confounds financing decisions with the mechanical autocorrelation of leverage. We propose and estimate a financing-based partial adjustment model that separates the effects of financing decisions on leverage evolution from mechanical evolution. The speed of adjustment (SOA) is firm-specific and stochastic, and active targeting of capital structure has a multiplier effect that depends on the size of financial deficit. Overall, we find expected SOA from active rebalancing (30%) more than doubles what is expected from mechanical mean reversion alone (13%).     

The impact of purchasing strategy-structure (mis)fit on purchasing cost and innovation performance

The organizational design literature strongly supports the notion of “structure follows strategy”, and suggests that a misfit between the two has a negative effect on performance. Building on this line of argument, we examine to what extent the (mis)fit between purchasing strategy and purchasing structure impacts purchasing performance. We focus on cost and innovation purchase category strategies, and examine how the deviation from an ideal purchasing structure defined along three dimensions (centralization, formalization, and cross-functionality) impacts purchasing performance. Analysing data collected from 469 firms in ten countries, we demonstrate that a strategy-structure misfit negatively impacts purchasing performance in both cost and innovation strategies. We also find that purchasing proficiency is a mediator in this relationship between misfit and performance. Our findings aid managerial decision making by empirically validating the necessity of having the right purchasing structure for successfully executing different purchasing strategies.     

Geography and capital structure

We investigate the impact of geographic location on firms’ capital structure decisions. We find strong evidence that location of a firm influences its capital structure. In particular, we find that centrally located firms have lower leverage ratios than do remotely located ones. Moreover, consistent with the hypothesis that those remotely located firms face more severe adverse selection problems, the effect of geographic location on capital structure is more pronounced when information asymmetry is higher. We further examine alternative explanations of the negative relation between firm geographic proximity and capital structure and show that the financial constraint effect and industry clustering effect do not explain our results. Copyright © 2016 ASAC. Published by John Wiley & Sons, Ltd.     

Are microfinance markets monopolistic?

Do microfinance institutions (MFIs) operate in a monopoly, monopolistic competition environment or are their revenues derived under perfect competition markets? We employ the Panzar–Rosse revenue test on a global panel data to assess the competitive environment in which MFIs of five selected countries operate: Ecuador, India, Indonesia, Peru and Philippines, over the period 2005–2009. We estimate the static and the dynamic revenue tests, with analyses of the interest rate and the return on assets. We control for microfinance-specific variables such as capital-assets-ratio, loans-assets and the size of the MFI. The analyses also account for the endogeneity problem by employing the fixed-effects two-stage least squares and the fixed-effects system generalized method of moments. Our results suggest that MFIs in Peru and India operate in a monopolistic environment. We also find weak evidence that the microfinance industry in Ecuador, Indonesia and Philippines may operate under perfect competition.