Chaotic Roll Motions of Ships in Regular Longitudinal Waves

Parametric resonance can lead to dangerously large rolling motions, endangering the ship, cargo and crew. The QR-faetorization method for calculating （LCEs） Lyapunov Characteristic Exponents was introduced; parametric resonance stability of ships in longitudinal waves was then analyzed using LCEs. Then the safe and unsafe regions of target ships were then identified. The results showed that this method can be used to analyze ship stability and to accurately identify safe and unsafe operating conditions for a ship in longitudinal waves.

Physical and dynamic mechanical behaviors of marble after heat treatment in quasi-vacuum and air-filled environments

The dynamic mechanical properties of rock specimens after thermal treatment in the air-filled environment(AE:i.e.,at the free surface)have been extensively investigated,yet they are rarely estimated in the quasi-vacuum environment(VE:i.e.,far from free surface),which is of special importance in engineering practice.Several precise laboratory tests(i.e.,split Hopkinson pressure bar test)on marble samples in both AE and VE were performed to investigate physical and dynamic mechanical behaviors of marble after heat treatment(25℃ to 900℃)in AE and VE.The tests results demonstrate that related properties of marble could be divided into three different stages by corresponding critical temperatures of 300℃ and 600℃,at which heat damage factors are 0.29(0.30)and 0.88(0.92)in VE(AE),respectively.The thermal damage developes more fully in AE than in VE.The thermal environment plays an important role,especially in Stage 3.Specifically,a conspicuous difference(greater than 20%)between AE and VE occurs in corresponding dynamic strength and the anti-deformation capacities of tested marble specimen.The influence of heat damage of rock is very important and valuable in engineering practice,particularly when the temperature is very high(greater than 600℃).

Framing and Reframing the Digital Divide Policy in Taiwan： Consensus and Conflict

This paper explores key policy issues of national information and communication technology development to identify the gap between the heterogeneity in issues pertaining to the ＂digital divide＂. How this issue is cast often as a problem to be solved in recent years. On the public policy front, a series of reports issued by Taiwan Residents policymakers were endeavored to address universal services and digital divide issues. Government also has taken various steps to mitigate the disparity in opportunities to access the Internet （e.g., ＂e-Taiwan＂ for broadband services, ＂M-Taiwan＂ for broadband infrastructure and heterogeneous network services, and ＂i-Taiwan＂ for ubiquitous networks and digital convergence by Taiwan＇s Cabinet）. However, when policymakers worked to craft solutions to the pressing societal concern, they found lots of policy agendas need to redefine to foster greater understanding and enlighten practice for policy going forward. An examination of conflicting narratives within policy has been conducted, which identified not only the earlier debates were framed, but also key agendas of the most studied and empirical data used among them. The article attempts to examine the topic from a longitudinal perspective by using sets of documents revealed a tendency over time to explore how particular the agendas and debates of ＂digital divide＂ were framed. The study traced back to policy debates from cultural, economic, educational, and political perspectives at various Internet diffusion stages. The results provide useful insights into the study and discussion on new convergence policy making implications.

The Impact of Trade Facilitation on Economic Development： A Case of East African Community （EAC）

This study examined the impact of trade facilitation on economic development, particularly the impact of customs environment on trade flows over the period from 1995 to 2010. Five countries of the East African Community （EAC）, namely, Tanzania, Kenya, Uganda, Rwanda, and Burundi, are involved. The study employs a gravity model for estimating bilateral trade flows between the EAC partner states. The ordinary least square （OLS） technique is adopted and applied for the regression analysis by using the Stata 10.0 software. Results suggest that, the customs environment of the importer is significant and possesses a strongly positive impact on East African trade flows. Results also find that the customs environment of the exporter is insignificant, even though it shows a negative relationship with the East African trade flows, hence a negative determinant. East African countries have to improve their customs environment, especially when undertaking an importation, in order to boost the overall trade flow in the block. They should also improve other trade facilitation indicators, such as port efficiency, regulatory environment, and infrastructure. The aid for trade, in terms of technical and financial assistance, should also be enhanced for the development of infrastructure, including roads, railways, ports, bridges, and border posts.

Effect of cilostazol on cerebral arteries in secondary prevention of ischemic stroke

Objective To compare the effects of cilostazol on cerebral arteries and cerebrovascular blood flow in secondary prevention of ischemic stroke, with those of aspirin. Methods Sixty-eight patients who had ischemic stroke during the recent 1-6 months were recruited and randomized into cilostazol or aspirin group. Cerebrovascular condition was assessed by magnetic resonance angiography （MRA） and transcranial doppler ultrasonography （TCD） at the beginning of the study and after 12-month medication. Results During the clinical follow-up, ischemic stroke recurred in 2 patients in cilostazol group, while in aspirin group, one case of ischemic stroke recurrence and one case of acute myocardial infarction were found. MRA revealed that in aspirin group, the percentages of patients experiencing aggravation and attenuation of cerebrovascular condition were 3.3% and 6.7%, respectively, while in aspirin group, they were 3.3% and 10%, respectively. Moreover, TCD revealed that 26.9% of the patients in aspirin group and 14.3% of the patients in cilostazol group experienced aggravation of cerebrovascular condition. However, the systolic peak flow velocity of the previously abnormal arteries increased by 42.9% after 12-month medication of cilostazol, which was significantly higher than that after aspirin medication （27.5%） （P = 0.04）. Furthermore, as a major side effect of antiplatelet therapy, the frequrency of bleeding was much less in cilostazol group （0 case in cilostazol group vs 5 in aspirin, P 〈 0.05）. Conclusion Cilostazol is as effective as aspirin in preventing the aggravation of cerebral arteries in secondary prevention of ischemic stroke. Besides, it is more safe. Cilostazol can increase the systolic peak flow velocity of cerebral arteries, which may improve the blood supply of focal ischemia.

How to reach the orbital configuration of the inner three planets in HD 40307 planet system?

The formation of the present configuration of three hot super-Earths in the planet system HD 40307 is a challenge to dynamical astronomers.With the two successive period ratios both near and slightly larger than 2,the system may have evolved from pairwise2:1 mean motion resonances(MMRs).In this paper,we investigate the evolutions of the period ratios of the three planets after the primordial gas disk was depleted.Three routines are found to probably result in the current configuration under tidal dissipation with the center star,they are:(i)through apsidal alignment only;(ii)out of pairwise 2:1 MMRs,then through apsidal alignment;(iii)out of the 4:2:1 Laplace Resonance(LR),then through apsidal alignment.All the three scenarios require the initial eccentricities of planets～0.15,which implies a planetary scattering history during and after the gas disk was depleted.All the three routines will go through the apsidal alignment phase,and enter a state with near-zero eccentricities finally.We also find some special characteristics for each routine.If the system went through pairwise 2:1 MMRs at the beginning,the MMR of the outer two planets would be broken first to reach the current state.As for routine(iii),the planets would be out of the LR at the place where some high-order resonances are located.At the high-order resonances 17:8 or 32:15 of the planets c and d,the system will possibly enter the current state as the final equilibrium.

A novel method of periodic orbit computation in circular restricted three-body problem

Periodic orbits are fundamental keys to understand the dynamical system of circular restricted three-body problem, and they play important roles in practical deep-space exploration. Current methods of periodic orbit computation need a high-order analytical approximate solution to start the iteration process, thus making the computation complicated and limiting the types of periodic orbits that can be obtained. By utilizing the symmetry of the restricted three-body problem, a special kind of flow function is constructed, so as to map a state on the plane of symmetry to another state that also lies in this plane. Based on this flow function, a new method of periodic orbit computation is derived. This method needs neither a starting analytic approximation nor the state transition matrix to be computed, so it can be conveniently implemented on a computer. Besides, this method is unaffected by the nonlinearity of the dynamical system, allowing a large set of periodic orbits which have x-z plane symmetry to be computed numerically. As examples, some planar periodic orbits (e.g. Lyapunov orbit) and spatial periodic orbits (e.g. Halo orbit) are computed. By further combining with a differential correction process, the method introduced here can be used to design resonant orbits that can jump between different resonant frequencies. One such resonant orbit is given in this paper, verifying the efficiency of this method.