“防急”“反停”:朝鲜半岛无核化需推力再聚“合力”

2019年,东北亚相关国家为解决朝核问题进行了多轮首脑会晤,特别是在中朝领导人成功实现互访之后,对中国经略好周边外交提出了更高要求。特殊的地缘条件使朝鲜成为中国经略周边外交的重要战略支点,朝鲜的稳定对中国至关重要。同时,"以拖待变"、"先行弃核"、无核化概念存疑等因素深刻影响着美国对朝鲜的态度,现在美国采取不急于让朝弃核的"温水煮青蛙"方式危害巨大。因此,半岛无核化过程中必须要"防急"更要"反停",也就是不仅要防止"快刀斩乱麻"、而且要反对"温水煮青蛙"这两种极端现象的发生就成为学术界极为关注的课题。中国作为负责任的大国必须为朝鲜半岛无核化提供助力,贡献更多中国智慧和方案,形成解决问题的国际社会"合力",减少"阻力",为国际社会对"朝核永远在路上"和朝鲜事实"拥核"的担心交上满意答卷。

Effects of acute aerobic exercise on motor response inhibition:An ERP study using the stop-signal task

Purpose： The purpose of this study was to determine the effects of acute exercise on motor response inhibition using both behavioral and electrophysiological approaches. Methods： The P3 and N1 event-related potential （ERP） components were recorded while performing a stop-signal task in 21 college students following a moderately intense acute exercise bout for 30 min and a sedentary control session that involved reading. Results： Acute exercise induced a shorter stop signal response time （SSRT） as compared to control; however, the go response time （Go RT） remained unchanged. In examining the ERP data, acute exercise increased both P3 amplitude and latency but did not affect the N1 component. Conclusion： Acute exercise has a selective and beneficial effect on cognitive function, specifically affecting the motor response inhibition aspect of executive function. Furthermore, acute exercise predominately impacts later stages of information processing during motor response inhibition, which may lead to an increase in attentional resource allocation and confer the ability to successfully withhold a response to achieve motor response inhibition.

Effect of Solid Retention and Hydraulic Retention Times on Membrane Fouling in Membrane Bioreactor

In this bench scale submerged membrane bioreactor, effect of solid retention time and hydraulic retention time on membrane fouling propensity has been studied. This experiment is carried out at different solid retention time of 5, 10, 30, 70 and 98 days; and fouling behavior of membrane bioreactor is investigated. Average effluent quality is found to be 88.14%-94.38%. The experiment with different hydraulic retention is carried for 3 to 4 days and fouling behavior has been investigated. The effluent quality at different hydraulic retention time of 1, 2, 3, 5, 10 and 24 hours has been investigated. This paper aims to search optimal values of solid and hydraulic retention times at which lower fouling and higher organic removal efficiency can be obtained. This study has been mainly focused on operating parameters rather than microbial structure, effect and analysis of activated sludge to membrane fouling.

Effect of Sludge Retention Time on Nitrite Accumulation in Real-time Control Biological Nitrogen Removal Sequencing Batch Reactor

In this study,four sequencing batch reactors(SBR),with the sludge retention time(SRT)of 5,10,20 and 40 d,were used to treat domestic wastewater,and the effect of SRT on nitrite accumulation in the biological nitrogen removal SBR was investigated.The real-time control strategy based on online parameters,such as pH,dissolved oxygen(DO)and oxidation reduction potential(ORP),was used to regulate the nitrite accumulation in SBR. The model-based simulation and experimental results showed that with the increase of SRT,longer time was needed to achieve high level of nitritation.In addition,the nitrite accumulation rate(NAR)was higher when the SRT was relatively shorter during a 112-day operation.When the SRT was 5 d,the system was unstable with the mixed liquor suspended solids(MLSS)decreased day after day.When the SRT was 40 d,the nitrification process was significantly inhibited.SRT of 10 to 20 d was more suitable in this study.The real-time control strategy combined with SRT control in SBR is an effective method for biological nitrogen removal via nitrite from wastewater.

Real Time Math Simulation of Contact Interaction during Spacecraft Docking and Berthing

Contact reactions of guide surfaces of assembly interfaces lead to the decreasing of theirs lateral and angular misalignments. The focus of this paper is the development of algorithms for computation of guide surfaces contact forces with acceptable engineering accuracy for real time simulation of assembly operations. Therefore, each complex guide surface is described as a set of contacting elements. Each contacting element for one＇s part can be represented by a finite set of geometric primitives which geometry is described by low order algebraic equations. So contact conditions and geometric parameters for all pairs of primitives are determined by analytical expressions. Math models are developed for two classes of contact interaction. The first class includes all cases when each contacting surface has several degrees of freedom of motion. Therefore, contact reactions introduced into differential equations of motion are calculated by using contacting elements penetrations, stiffness and damping parameters. The second class corresponds to all cases when one of contacting surfaces has insignificant inertia and only one degree of freedom of relative displacement counteracted by a spring. Here contact reactions are calculated from spring tension with any practical accuracy. This is very useful in some practical applications. Presented algorithms provide real time simulation together with some approaches for reduction of redundant comnutations.

Counter-Rotating Type Tidal Stream Power Unit Moored by Only One Cable

The authors have proposed that a counter-rotating type tidal stream power unit mounted rigidly on a pile, and outputs of the power unit and forces acting on the pile were investigated experimentally at a previous paper, A single propeller makes the pile undertake a reaction force orthogonal to the stream direction. On the contrary, proposed counter-rotating propellers do not require undertaking the reaction force of the pile, because the rotational torque is counter-balanced in the unit. This advantage means that the unit can be moored by only one cable. Continuously, this paper proposes such a power unit with tandem propellers, and experimentally investigates a behavior of the unit floating in a water channel. The vibrations of the power unit are induced from not only the individual but also the interacting rotations of the front and the rear propellers.

Sinking of particulates ^(234)Th_(xs),~7Be and ^(210)Pb_(xs) in the Changjiang estuary,China

The time scale of transport and reaction processes in the ocean can be evaluated using natural radionuclides of different half-lives.In the present study,we evaluated the residence times of particulate reactive radionuclides 7 Be,210 Pb xs and 234 Th in the Changjiang (Yangtze River) estuary,which is a high turbidity estuary,in June,2006.The residence times of particulate 7 Be,234 Th xs and 210 Pb xs in the Changjiang estuary were calculated to be 0.7-20.4,0.18-4.1 and 0.6-89.8 d,respectively.The obtained residence times of those nuclides are comparable with those of other estuaries and bays.For 234 Th xs and 7 Be,the residence times decreased with increasing concentrations of suspended particulate matter (SPM);however,those of 210 Pb xs increased.Moreover,scavenging residence times of 234 Th and 7 Be increased from coast to offshore,while those of 210 Pb xs decreased.

Steady State and Dynamic of Gluconic Acid Production by Aspergillus Niger

Batch and continuous fermentation ofgluconic acid production has been studied. The kinetic parameters of the fermentation process were determined from the batch experimental data. The continuous fermentation was modeled to be carried out in a stirred tank reactor. The effect of hydraulic retention time on the steady state continuous fermentation process of glucose by Aspergillus niger to produce gluconic acid was investigated. The result showed that increasing the hydraulic retention time caused the cell amount and gluconic acid concentration at the outlet stream increased but the glucose concentration at the outlet stream decreased. The steady state simulation result was useful for fermenter size determination. Dynamic behaviour of gluconic acid production through fermentation by Aspergillus niger was also studied for a fermenter with 24 h hydraulic retention time. Applying step change of inlet substrate concentration resulted in first order response of cell, substrate and product concentration with all having positive gain. On the other hand, applying step change of inlet cell concentration has resulted in positive gain for cell and product concentration and negative gain for substrate concentration with first order response for all those three parameters.

Unplanned Shutdown Frequency Prediction of FBR MONJU Using Fault Tree Analysis Method

In order to evaluate the operational reliability of Japanese FBR （fast breeder reactor） MONJU, frequencies of important intermediate events and equipment failures resulting during reactor automatic trip are predicted using FTA （fault tree analysis） technique for the plant system model. The targeted devices are the following： PHTS （primary heat transport system）, SHTS （secondary heat transport system）, WS （water and steam system）, PPS （plant protection system） and PCS （plant control system）. In this paper, the frequency of automatic reactor trips was estimated by extracting and analyzing the important intermediate events and equipment failures covering all the derived fault trees of these systems. The analyses predicted 1.2/RY （reactor year） the value of unplanned shut down frequency by the internal factor of the system. The largest contributed event was function failure of SHTS accounting for 42.6% of total events followed by PHTS with 40.1%. The contribution factor of WS was only 4.4%.

Frog community responses to recent American bullfrog invasions

Native species may decline quickly when confronted with an exotic species to which they are not adapted. The extent of decline may depend on the abundance of an invader and the length of time since it first arrived in the community （residence time）, and the interaction between these two variables. We tested these effects using data on the effects of American bullfrog Lithobates catesbeianus invasion on native frog communities in 65 permanent lentic waters on islands in the Zhoushan Archipel- ago, China. We examined variation in native frog abundance and species richness in relation to features of the American bullfrog invasion, habitat disturbance, characteristics of the water body and fish communities and the presence of red swamp crayfish. Bullfrog invaded sites had lower native frog density and species richness, higher submerged vegetation cover and greater fre- quency of repairs to the water body than did non-invaded sites. The minimum adequate general linear mixed models showed that both native frog density and species richness were negatively related to post-metamorphosis bullfrog density, and that native frog species richness was also positively related to the vegetation cover. There was no effect on either native frog density or species richness of residence time or its interaction with bullfrog density, or of the abundance of bullfrog tadpoles. The results suggested that post-metamorphosis bullfrogs had impacts on native frog communities in the islands, and that the extents of these impacts are proportional to post-metamorphosis bullfrog density

Control mechanism for the upper airway collapse in patients with obstructive sleep apnea syndrome: a finite element study

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent collapses of the upper airway, which lead to repetitive transient hypoxia, arousals and finally sleep fragmentation. Both anatomical and neuromuscular factors may play key roles in the pathophysiology of OSAS. The purpose of this paper was to study the control mechanism of OSAS from the mechanical point of view. A three-dimensional finite element model was developed, which not only reconstructed the realistic anatomical structure of the human upper airway, but also included surrounding structures such as the skull, neck, hyoid, cartilage and soft tissues. The respiration process during the normal and apnea states was simulated with the fluid-structure interaction method (FSI) and the computational fluid dynamics method (CFD). The airflow and deformation of the upper airway obtained from the FSI and the CFD method were compared and the results obtained under large negative pressure during an apnea episode were analyzed. The simulation results show that the FSI method is more feasible and effective than the CFD method. The concave configuration of the upper airway may accelerate the collapse of the upper airway in a positive feedback mechanism, which supplies meaningful information for clinical treatment and further research of OSAS.