大数据环境下支持多关键字的可搜索公钥加密方案

云计算为大数据提供了强大的数据处理平台,而数据的安全和隐私问题也引起了人们的高度关注.本文提出了一个新的大数据环境下支持多关键字的无需安全信道的无证书可搜索公钥加密方案,并且证明了在随机预言机模型下,本文方案能够抵抗关键字猜测攻击.同时,效率分析表明,与Peng等方案相比,本文方案降低了计算代价和通信代价.     

朱仙庄煤矿塌陷水域水文地球化学特征及污染评价

煤矿塌陷导致的环境问题日益显现,尤其是塌陷水域的水环境问题直接影响到矿区水资源利用。通过对朱仙庄塌陷塘常规离子(K~+,Na~+,Ca~(2+),Mg~(2+),Cl~-,SO_4~(2-),HCO_3~-)及重金属离子(Cd~(2+),Cr~(3+),Mn~(2+),Pb~(2+))的测定来分析塌陷塘水文化学特征,并利用单因子评价法、内梅罗指数法对水域重金属离子做出污染评价。结果表明,塌陷塘水化学类型为:I,II,III塘均为HCO_3-Na型;IV塘HCO_3-Ca型。重金属含量均符合《地表水环境质量标准》(GB3838—2002)II类水质标准。单因子评价法与内梅罗指数法评价结果显示,塌陷塘水质良好,基本无污染。     

Living on the edge: feeding of subtropical open ocean copepods

The objective of this study was to provide quantitative information on environmental feeding rates of warm water oceanic epipelagic copepods. We determined clearance rates at 23 °C for various particle size ranges in shipboard studies in the western oligotrophic subtropical Atlantic Ocean for females of the calanoid species Clausocalanus furcatus and Mecynocera clausii. These in situ clearance rates were then applied to the various particle size ranges of environmental particle spectra of auto‐ and heterotrophs at different depths from three stations in the western Atlantic. After calculating the metabolic demands of each of these two copepod species and applying an assimilation efficiency of 90%, we determined that C. furcatus meets its metabolic demands in all six cases, and M. clausii in two of six cases. Clausocalanus furcatus would also meet its energy demands at 25 °C, where it is often found, while M. clausii at 20 °C, where it is regularly found, would cover its metabolic needs in four of six cases. It is hypothesized that these species, and most likely most of the other co‐occurring copepod species, are limited in their abundance by food availability, or, better said, are ‘living on the edge’ in relation to food abundance.     

Funding Science that Links to Decisions: Case Studies Involving Coastal Land Use Planning Projects

Many reports have noted that a significant portion of coastal science that is funded to help society address resource management issues does not actually link to decisions. A few studies and reports have offered valuable but general advice on what the funders of this science can do to better link science with decisions; there are fewer still published empirical case studies assessing the impacts of innovative funder methods for getting more science used by intended audiences. Here, we report on three case studies involving new tools and science to help land use planners better protect coastal resources. Our qualitative analysis indicates that funder efforts to bring scientists and users into greater alignment did improve the extent to which science linked to decisions. However, these cases show that funders can and should do more if the paramount motivation behind the science is to address societal problems rather than generate new knowledge. Based on these findings, we assert that funders need to focus significantly more attention and resources on the user engagement aspect of science projects, making strong user engagement methods as important as strong biophysical science or social science methods.     

Palaeointensity results for historic lavas from Mt Etna using microwave demagnetization/remagnetization in a modifiedThellier-type experiment

The bane of conventional Thellier-type palaeointensity experiments is the thermal alteration of the samples during experimentation. However, high-frequency microwaves can be used to stimulate the magnetic minerals directly, thus eliminating the need for the bulk sample to be heated ( Walton et al . 1993 ). The microwave technique has been successfully applied to ceramics ( Shaw et al . 1996 , 1999 ), and here we present results for historic lavas from Mt Etna, Sicily. 20 samples were randomly selected from 10 different historic flows dating from 1843 to 1983. Hysteresis parameters were monitored as a check for alteration during experimentation and minimal alteration was found. Rock-magnetic analysis and AF plus microwave demagnetizations were carried out on all samples, and microwave intensity analysis was carried out on those samples that were stable to microwave demagnetization (16 in total). With one exception, all samples gave high-quality intensity results. Two or three subsamples from each sample were investigated and a weighted average calculated to give a single estimate of the field. When the intensity values were compared with the SV model based on direct observatory measurements ( Bloxham & Gubbins 1985 ), it was found that those samples that contained a high multidomain (MD) component gave intensity values around 20 per cent lower than expected. This can be explained by the cooling rate effect ( Dodson & McClelland-Brown 1980 ) and/or the presence of an MD component ( McClelland et al. 1996 ). Those samples with the lowest numbers of MD grains gave field values which, within error, were the same as those for the model, or slightly too high: this is compatible with the cooling rate effect.     

冬季中国东部海区热通量变化与中国气温降水的关系

利用OAFlux月平均热通量、NCEP/NCAR（1958—2006年）再分析和全国160个站的月降水、气温等资料,采用相关分析、合成分析等方法,分析了中国东部海区海气界面热通量变化特征及其与中国冬、春季降水、气温的关系。研究表明,中国东部海区为潜热通量和感热通量年际变化的关键区,冬季变化最为显著,具有明显的年际和年代际变化特征,热通量的增强趋势明显。热通量的年代际变化与同期冬季中国华南降水存在明显正相关,与华北降水存在负相关、与气温存在显著正相关。1983年气候突变前热通量年际变化与同期中国长江下游地区降水有很好的负相关。突变后热通量年际变化与同期淮河流域降水存在显著负相关;与后期春季中国两河流域降水存在显著负相关,与两河流域气温存在显著正相关。     

春季中国东海黑潮区大气热源异常对中国东部降水的影响

采用ERA-interim逐日再分析数据集与中国东部389个站逐日降水资料,通过相关和合成分析讨论了不同时间尺度上,春季中国东海黑潮区上空大气热源异常对东亚大气环流和中国东部降水的影响。观测分析表明,春季中国东海黑潮区上空为一显著的大气热源,大气对该热源的响应在不同时间尺度上表现出不同的形式。在较长时间的季节和年际尺度上,春季中国东海黑潮区大气热源增强时,可在大气对流层低层强迫出偏南气流,同期春季及后期夏季西太平洋副热带高压增强并西伸,相比于热源低值年西北太平洋副热带地区为一反气旋式异常环流所控制,中国长江中下游以南地区降水增多;反之亦然。与年际和季节时间尺度不同,在较短的天气时间尺度上,中国东海黑潮区上空大气热源增强可在其下方强迫出气旋式异常环流。大气热源的增强与中国东部对流层低层气旋式异常环流的东移有关,相应地在中国东部地区出现了显著的降水增多。     

Dynamical controls on the diurnal cycle of temperature in complex topography

We examine the climatological diurnal cycle of surface air temperature in a 6 km resolution atmospheric simulation of Southern California from 1995 to the present. We find its amplitude and phase both have significant geographical structure. This is most likely due to diurnally-varying flows back and forth across the coastline and elevation isolines resulting from the large daily warming and cooling over land. Because the region’s atmosphere is generally stably stratified, these flow patterns result in air of lower (higher) potential temperature being advected upslope (downslope) during daytime (nighttime). This suppresses the temperature diurnal cycle amplitude at mountaintops where diurnal flows converge (diverge) during the day (night). The nighttime land breeze also advects air of higher potential temperature downslope toward the coast. This raises minimum temperatures in land areas adjacent to the coast in a manner analogous to the daytime suppression of maximum temperature by the cool sea breeze in these same areas. Because stratification is greater in the coastal zone than in the desert interior, these thermal effects of the diurnal winds are not uniform, generating spatial structures in the phase and shape of the temperature diurnal cycle as well as its amplitude. We confirm that the simulated characteristics of the temperature diurnal cycle as well as those of the associated diurnal winds are also found in a network of 30 observation stations in the region. This gives confidence in the simulation’s realism and our study’s findings. Diurnal flows are probably mainly responsible for the geographical structures in the temperature diurnal cycle in other regions of significant topography and surface heterogeneity, their importance depending partly on the degree of atmospheric stratification.     

Ocean-to-Atmosphere Forcing in the Vicinity of the Sea Surface Temperature Front in the East China Sea—Seasonal Variations

采用一系列高分辨率的卫星资料研究了我国东部海区的海洋温度锋对局地大气的强迫作用及其季节变化.分析表明,当春季海洋锋增强时,海温与海表面风速之间存在明显的正相关关系,并且在海洋锋的暖(冷)侧形成海表风的辐合(辐散),表现为海洋对大气的强迫作用.海温对表面风场的影响程度与海洋锋的强度成正比,春季影响程度最大,夏、秋季最小.海洋锋对其附近的总降水、对流、层云降水均有影响,尤其在春季海洋锋暖侧的降水强度增大,对流降水的频次增多,“雨顶”高度也有明显的抬升.暖流对大气的影响不仅局限在边界层,其影响可达整个对流层.另外,分析发现对流降水对海温的响应比层云降水更加敏感.研究还表明,暖流上空高、低云呈现相反的年循环特点,冬季多0.5～2 km的边界层云,夏季多云底在10 km以上的高云.深对流云集中出现在3～6月,从冬季到初夏,30％以上的云量中心抬高了接近8km.春季和初夏在海洋锋的暖侧频繁地出现深对流活动.     

粤港澳大湾区某地天然放射性环境调查与评价

天然放射性辐射是衡量优质人居环境的一项重要指标,在城市建设中开展放射性环境调查必不可少.2020年5月-10月,以(250～500)m×(50～100)m的网度布设测量点,在粤港澳大湾区某地开展1:25000环境地表γ辐射剂量率测量.结果表明,区内整体辐射环境未发生明显变化,且处于正常水平.区内环境地表γ辐射水平可分为城镇人口密集区、基岩出露区和原野区3类,其中人口密集区的环境地表γ辐射水平略高于天然本底值2.48％～13.73％;基岩出露区环境地表γ辐射水平普遍高于天然本底值3.92％～65.29％;原野区环境地表γ辐射水平普遍低于天然本底值17.65％～40.20％,共发现10处异常高数值区(点),均与区内裸露的花岗岩及断裂构造带密切相关.居民所受环境地表γ辐射所致公众人均年有效剂量平均值为0.693 mSv·a-1,与全国辐射环境质量水平相当.圈定异常区4处,区内常驻人员需做好防护措施,或减少停留时间.