The arrangement in mean elements space of the periodic orbits close to that of the Moon

In a simplified model of the Earth-Moon-Sun system based on the restricted circular 3-dimensional 3-body problem, it is possible to find numerically a set of 8 periodic orbits whose time evolutions closely resemble that of the Moon's orbit. These orbits have a period of 223 synodic months (i.e. the period of the Saros cycle known for more than two millennia as a means of predicting eclipses), and are characterized by a secular rotation of the argument of perigee . Periodic orbits of longer durations exhibiting this last feature are very abundant in Earth-Moon-Sun dynamical models. Their arrangement in the space of the mean orbital elements- for various values of the lunar mean motion is presented.     

The role of bathymetry and directional wave conditions on observed crescentic bar dynamics

Nearshore sandbars are important features in the surf zone of many beaches because they strongly influence the mean circulation and evolving morphology. Due to variations in wave conditions, sandbars can experience cross-shore migration and vary in shape from alongshore uniform (shore-parallel) to alongshore rhythmic (crescentic). Sandbar dynamics have been studied extensively, but existing observational studies usually do not quantify the processes leading to crescentic bar formation and straightening. This study analyses the dynamics of crescentic bar events at the fetch-limited beach of Castelldefels (northwestern Mediterranean Sea, Spain) using 7.5 years of hourly time-exposure video images and detailed wave conditions. The results show that, despite the generally calm wave conditions, the sandbars were very dynamic in the cross-shore and longshore directions. They often migrated rapidly offshore during storms (up to 70 m in one day) and more slowly onshore during post-storm conditions. Crescentic bars were often present at the study site (48% of the time), but only when the sandbar was at least 10 m from the shoreline. They displayed a large variability in wavelengths (100–700 m), alongshore migration speeds (0–50 m/day) and cross-shore amplitudes (5–20 m). Wavelengths increased for larger bar–shoreline distances and the alongshore migration speeds were strongly correlated with the alongshore component of the radiation stresses. Crescentic patterns typically developed during low–medium energetic waves with limited obliquity ( $\theta \lesssim 20$° at 10 m depth), while bar straightening occurred during medium–high energetic waves with strong oblique angles of incidence ( $\theta \gtrsim 15$°). Overall, this study provides further proof for the important role of wave direction in crescentic bar dynamics and highlights the strong dependence of crescentic bar development on the initial bathymetric configuration.     

新地球观

One of the most important achivements on science in 20th century is the new recognition on the Earth:the Earth,out of the other planets, exhibits very peculiar features because it has an extremely complex and active periphery part (surfacial layers). This periphery part is an open system sustained by inputting solar energe , which is captured , transfered and stored by life. Through the system , cyclings of matters and energe flow are driven and regulated by life activities. This system is self-equilibrated,self-controlled and far away from astrophysical and thermodynamic equilibria mainly because of life and life activities.
Development of human calture influences increasingly on流Earth's periphery system , at last , the natural biosphere that has existed for 3 billion years on the Earth's surface will inavoidably be replaced by so called "noosphere",which is man一reconstructed,man-controlled and unstable system. Thus the fate of the Earth,to a great extent,will be determined by the direction of human calture evolution.
     

福建省第三产业发展的区域比较分析

运用可拓工程方法和主成分分析方法建立了福建省第三产业发展水平的综合评判物元模型。模型的输出结果表明：福建省各地区第三产业发展水平差距悬殊；综合关联度将第三产业发展水平划分成4个等级，单指标关联度则揭示了各地区第三产业发展的优、劣势。     

黄河影响下开封城市的历史演变

河流对城市的形成和发展起着重要的作用,古人形象地把其比喻为“城市之血脉”。文章从不同的历史时期黄河及其分支对开封城市演变的影响进行分析,得出黄河与开封城市的关系存在着利与害的统一。开封城市的历史发展,即得益于黄河充足的水源,又受害于其频繁的决溢、泛滥、改道。因此,要采用先进的科学技术对黄河进行综合治理开发,使其恢复它应有的美好环境,更好地造福于人民。     

The seismic hazard assessment of the Dead Sea rift, Jordan

The Dead Sea fault system and its branching faults represent one of the most tectonically active regions in the Middle East. The aim of this study is to highlight the degree of hazards related to the earthquake activities associated with the Dead Sea rift, in terms of speculating the possible future earthquakes. The present investigation mainly is based on available data and vertical crustal modeling of Jordan and the Dead Sea model for the Dead Sea basin with particular emphasis of the recent earthquake activities, which occurred on December 31st, 2003 (Mc = 3.7), February 11th, 2004 (strongest Mc = 4.9 R), and March 15th, 2004 (Mc = 4). The present research examines the location of the strong events and correlates them with the various tectonic elements in the area. The source mechanism of the main shock and the aftershock events is also examined. The analyses were based on the available short period seismogram data, which was recorded at the Natural Resources Authority of Jordan, Seismological Observatory. The seismic energy appears to have migrated from the south to the north during the period from December 31st up to March 12th, where the released seismic energy showed a migration character to the southern block of the eastern side of the Dead Sea, which led the seismic event to occur on March 15th.     

A pronounced dry event recorded around 4.2 ka in brine sediments from the northern Red Sea

Partly laminated sediments were sampled from the brine-filled, anoxic Shaban Deep basin in the northern Red Sea. At about 4200 cal yr BP more than two millennia of anoxic sedimentation is replaced by a sub-oxic facies strongly suggesting the episodic absence of the brine. At the same time stable oxygen isotopes from surface dwelling foraminifera show a sharp increase (within less than 100 yr) pointing to a strong positive salinity anomaly at the sea surface. This major evaporation event significantly enhanced the renewal of deep water and the subsequent ventilation of the small Shaban Deep basin. The timing and strength of the reconstructed environmental changes around 4200 cal yr BP suggest that this event is the regional expression of a major drought event, which is widely observed in the neighboring regions, and which strongly affected Middle East agricultural civilizations.     

Damage Survey of Water Supply Systems and Fragility Curve of PVC Water Pipelines in the Chi–Chi Taiwan Earthquake

Substantial damage to water supply systems, including water delivery pipelines, water treatment plants, reservoirs, and water storage tanks, was reported after the 1999 Chi–Chi Taiwan Earthquake. This paper first summarizes the damage survey and then presents the results of seismic fragility analysis for underground pipelines. Construction blueprints of the water delivery pipelines and repair work orders of 11 townships and cities in the disastrous area were digitized into a Geographical Information System (GIS) for analysis and assessment. With the aid of the GIS system, we found that PVC pipes made up 86% of water delivery pipelines while steel, cast iron, ductile iron, PE and others took the rest. Therefore, this paper focuses on the fragility analysis of PVC pipes. Three different methods were applied to derive the fragility relations between the PVC water pipes having nominal diameters (approximately inner diameters) greater than or equal to 65 mm and earthquake intensity parameters such as peak ground acceleration and peak ground velocity. The results were then examined with those of other countries. The discrepancy between our results and the empirical equation used by HAZUS, an earthquake loss estimation software developed by the Federal Emergency Management Agency was not significant.     

R＆D投入的区位模式与区域经济发展

基于对中国R＆D投入的区位模式的实证检验，从投入一产出绩效的角度认为集中投入的区位模式具有较强的适宜性。利用聚类分析技术，按照R＆D的投入强度和及其对经济的带动效应、科技化效应、产业化效应将中国各省区划分为6类地区，具有代表性的是科技化模式和产业化模式。其中前者适合于技术存置较高的少数地区，而后者具有较强的借鉴意义。     

Short-term beach–dune sand budgets on the north sea coast of France: Sand supply from shoreface to dunes, and the role of wind and fetch

Three experimental plots, covering the transition from the upper beach to the dune, on the North Sea coast of France were monitored at various intervals over a period of 18–24 months via high resolution terrain surveys in order to determine inter-site sand budget variability, as well as patterns and processes involved in sand exchanges between the upper beach and dune. The wind regime consists of a fairly balanced mix of moderate (80% of winds are below 8 m/s) onshore, offshore and shore-parallel winds. Sustained dune accretion over several years depends on the periodic local onshore welding of shoreface tidal banks that have developed in the storm- and tide-dominated setting of the southern North Sea. The only site where this has occurred in the recent past is Calais, where bank welding has created a wide accreting upper beach sand flat. At this site, significant sand supply from the subtidal sand bank reservoir to the upper beach flat occurred only once over the 18-month survey following a major storm. The bulk of the sand deposited over this large flat is not directly integrated into the adjacent embryo dunes by onshore winds but is progressively reworked in situ into developing dunes or transported alongshore by the balanced wind regime, thus resulting in alongshore stretching of the embryo dune system. The Leffrinckoucke site near Belgium shows moderate beach–dune mobility and accretion, while the Wissant site exhibits significant upper beach bedform mobility controlled by strong longshore currents that result in large beach budget fluctuations with little net budget change, to the detriment of the adjacent dunes. Accretion at these two sites, which are representative of the rest of the North Sea coast of France, is presently constrained by the absence of a shore-attached sand bank supply reservoir, while upper beach–dune sand exchanges are further limited by the narrow wave-affected upper beach, the intertidal morphology of bars and troughs which segments the aeolian fetch, and the moderate wind energy conditions. The balanced wind regime limits net sand mobilisation in favour of either the beach or the dune, and may explain the relatively narrow longshore morphology of the dune ridges bounding this coast.