反逻辑例外论对例外论有威胁吗?

逻辑例外论与反例外论的争论是近年来逻辑哲学领域研究的热点。以约特兰、威廉姆森、普莱斯特等为代表的反逻辑例外论者的主要观点是:(1)逻辑理论、逻辑方法与科学理论、科学方法都是连续的;(2)逻辑理论是可以修正的,且基于与科学理论一样的理由/根据予以修正;(3)逻辑不是先天的,逻辑真也不是分析的。这三个观点既是这场争论的导火索,也是这场争论的焦点所在。因此,本文试图通过从基本概念的清晰界定、逻辑理论层次的区分上对反逻辑例外论的观点(1)(2)予以质疑,指出反逻辑例外论的不完善之处;并通过在逻辑史中对作为学科的逻辑的本质的考察,深入探究逻辑例外论认为逻辑具有先天性的归结所在,进而指出,反逻辑例外论的观点(3)在“逻辑先天性”问题上的质疑对逻辑例外论来说是有威胁力的,需予以重视。这样看来,对逻辑例外论与和反例外论的争论,最好持一种开放的心态,允许对逻辑以更多视角予以考察研究,推动逻辑的繁荣发展以及人类求真道路的坚实与多元。

An NMOS output-capacitorless low-dropout regulator with dynamic-strength event-driven charge pump

In this paper,an NMOS output-capacitorless low-dropout regulator(OCL-LDO)featuring dual-loop regulation has been proposed,achieving fast transient response with low power consumption.An event-driven charge pump(CP)loop with the dynamic strength control(DSC),is proposed in this paper,which overcomes trade-offs inherent in conventional structures.The presented design addresses and resolves the large signal stability issue,which has been previously overlooked in the event-driven charge pump structure.This breakthrough allows for the full exploitation of the charge-pump structure's poten-tial,particularly in enhancing transient recovery.Moreover,a dynamic error amplifier is utilized to attain precise regulation of the steady-state output voltage,leading to favorable static characteristics.A prototype chip has been fabricated in 65 nm CMOS technology.The measurement results show that the proposed OCL-LDO achieves a 410 nA low quiescent current(IQ)and can recover within 30 ns under 200 mA/10 ns loading change.

Tuning the electronic conductance of REH_(x)(RE=Nd,Ce,Pr)by structural deformation

Hydride ion(H-)conductors have drawn much attention due to their potential applications in hydrideion-based devices.Rare earth metal hydrides(REH_(x))have fast H-conduction which,unfortunately,is accompanied by detrimental electron conduction preventing their application as ion conductors.Here,REH_(x)(RE=Nd,Ce,and Pr)with varied grain sizes,rich grain boundaries,and defects have been prepared by ball milling and subsequent sintering.The electronic conductivity of the ball-milled REH_(x)samples can be reduced by 2-4 orders of magnitude compared with the non-ball-milled samples.The relationship of electron conduction and miscrostructures in REH_(x)is studied and discussed based on experimental data and previously-proposed classical and quantum theories.The H-conductivity of all REH_(x)is about 10^(-4)to 10^(-3)S cm^(-1)at room temperature,showing promise for the development of H-conductors and their applications in clean energy storage and conversion.

Improving Satellite-Retrieved Cloud Base Height with Ground-Based Cloud Radar Measurements

Cloud base height(CBH) is a crucial parameter for cloud radiative effect estimates, climate change simulations, and aviation guidance. However, due to the limited information on cloud vertical structures included in passive satellite radiometer observations, few operational satellite CBH products are currently available. This study presents a new method for retrieving CBH from satellite radiometers. The method first uses the combined measurements of satellite radiometers and ground-based cloud radars to develop a lookup table(LUT) of effective cloud water content(ECWC), representing the vertically varying cloud water content. This LUT allows for the conversion of cloud water path to cloud geometric thickness(CGT), enabling the estimation of CBH as the difference between cloud top height and CGT. Detailed comparative analysis of CBH estimates from the state-of-the-art ECWC LUT are conducted against four ground-based millimeter-wave cloud radar(MMCR) measurements, and results show that the mean bias(correlation coefficient) is0.18±1.79 km(0.73), which is lower(higher) than 0.23±2.11 km(0.67) as derived from the combined measurements of satellite radiometers and satellite radar-lidar(i.e., Cloud Sat and CALIPSO). Furthermore, the percentages of the CBH biases within 250 m increase by 5% to 10%, which varies by location. This indicates that the CBH estimates from our algorithm are more consistent with ground-based MMCR measurements. Therefore, this algorithm shows great potential for further improvement of the CBH retrievals as ground-based MMCR are being increasingly included in global surface meteorological observing networks, and the improved CBH retrievals will contribute to better cloud radiative effect estimates.

关于存在预设失效的语义学探究

存在预设在经典逻辑中有着重要的地位。存在预设失效了的逻辑系统就会成为一种自由逻辑系统,不得不面对空名与真值间隙问题。本文基于这些自由逻辑系统讨论了如何为存在预设失效提供一个合适的语义解释:首先通过语义预设的概念来定义存在预设、将真值间隙定义为二值原则失效,而后比较了为真值间隙赋值的不同方案,最终在虚构主义的立场上指出,超赋值语义学在把空名看作虚构对象名称的同时保留了逻辑真,是较为理想的语义解释。

Recent progress towards mild-condition ammonia synthesis

Ammonia is essential for food and energy.Industrial ammonia synthesis via Haber–Bosch process is energy-intensive and releases large amount of CO2.Increasing research efforts are devoted to "green"ammonia synthesis.The present article reviews the recent progress in the fields of thermocatalytic, electrocatalytic, photocatalytic and chemical looping processes for dinitrogen reduction towards ammonia formation and discusses the challenges borne for mild-condition synthesis.

Climatology of Cloud-base Height from Long-term Radiosonde Measurements in China

Clouds are critical to the global radiation budget and hydrological cycle, but knowledge is still poor concerning the observed climatology of cloud-base height （CBH） in China. Based on fine-resolution sounding observations from the China Radiosonde Network （CRN）, the method used to estimate CBH was modified, and uncertainty analyses indicated that the CBH is good enough. The accuracy of CBH estimation is verified by the comparison between the sounding-derived CBHs and those estimated from the micro-pulse lidar and millimeter-wave cloud radar. As such, the CBH climatology was compiled for the period 2006-16. Overall, the CBH exhibits large geographic variability across China, at both 0800 Local Standard Time （LST） and 2000 LST, irrespective of season. In addition, the summertime cloud base tends to be elevated to higher altitudes in dry regions [i.e., Inner Mongolia and the North China Plain （NCP）]. By comparison, the Tibetan Plateau （TP）, Pearl River Delta （PRD） and Sichuan Basin （SCB） have relatively low CBHs （〈 2.4 km above ground level）. In terms of seasonality, the CBH reaches its maximum in summer and minimum in winter. A low cloud base tends to occur frequently （〉 70%） over the TP, PRD and SCB. In contrast, at most sites over the Yangtze River Delta （YRD） and the NCP, about half the cloud belongs to the high-cloud category. The CBH does not exhibit marked diurnal variation in summer, throughout all CRN sites, probably due to the persistent cloud coverage caused by the East Asia Summer Monsson. To the best of our knowledge, this is the first CBH climatology produced from sounding measurements in China, and provides a useful reference for obtaining observational cloud base information.

Effect of BaNH,CaNH,Mg3N2 on the activity of Co in NH3 decomposition catalysis

Development of active and non-noble metal-based catalyst for H2 production via NH3 decomposition is crucial for the implementation of NH3 as a H2 carrier.Co-based catalysts have received increasing attention because of its high intrinsic activity and moderate cost.In this work,we examined the effect of BaNH,CaNH and Mg3 N2 on the catalytic activity of Co in the NH3 decomposition reaction.The H2 formation rate ranks the order as Co-BaNH>Co-CaNH>Co-Mg3 N2≈Co/CNTs within a reaction temperature range of 300-550℃.It is worth pointing out that the H2 formation rate of Co-BaNH at 500℃reaches20 mmolH2 gcat-1 min-1,which is comparable to those of the active Ru/Al2 O3(ca.17 mmolH2 gcat-1 min1)and Ru/AC(21 mmolH2 gcat-1 min-1)catalysts under the similar reaction conditions.In-depth research shows that Co-BaNH exhibits an obviously higher intrinsic activity and much lower Ea(46.2 kJ mol-1)than other Co-based catalysts,suggesting that BaNH may play a different role from CaNH,Mg3 N2 and CNTs during the catalytic process.Combined results of XRD,Ar-TPD and XAS show that a[Co-N-Ba]-like intermediate species is likely formed at the interface of Co metal and BaNH,which may lead to a more energy-efficient reaction pathway than that of neat Co metal for NH3 decomposition.

The Significant Role of Radiosonde-measured Cloud-base Height in the Estimation of Cloud Radiative Forcing

The satellite-based quantification of cloud radiative forcing remains poorly understood,due largely to the limitation or uncertainties in characterizing cloud-base height(CBH).Here,we use the CBH data from radiosonde measurements over China in combination with the collocated cloud-top height(CTH) and cloud properties from MODIS/Aqua to quantify the impact of CBH on shortwave cloud radiative forcing(SWCRF).The climatological mean SWCRF at the surface(SWCRFSUR),at the top of the atmosphere(SWCRFTOA),and in the atmosphere(SWCRFATM) are estimated to be-97.14,-84.35,and 12.79 W m^(-2),respectively for the summers spanning 2010 to 2018 over China.To illustrate the role of the cloud base,we assume four scenarios according to vertical profile patterns of cloud optical depth(COD).Using the CTH and cloud properties from MODIS alone results in large uncertainties for the estimation of SWCRFATM,compared with those under scenarios that consider the CBH.Furthermore,the biases of the CERES estimation of SWCRFATM tend to increase in the presence of thick clouds with low CBH.Additionally,the discrepancy of SWCRFATM relative to that calculated without consideration of CBH varies according to the vertical profile of COD.When a uniform COD vertical profile is assumed,the largest SWCRF discrepancies occur during the early morning or late afternoon.By comparison,the two-point COD vertical distribution assumption has the largest uncertainties occurring at noon when the solar irradiation peaks.These findings justify the urgent need to consider the cloud vertical structures when calculating the SWCRF which is otherwise neglected.

Possible Trajectories of Agricultural Cropping Systems in China from 2011 to 2050

Predicting the possible impacts of future climate change on cropping systems can provide important theoretical support for reforming cropping system and adjusting the distribution of agricultural production in the future. The study was based on the daily data of future B2 climate scenario (2011-2050) and baseline climate condition (1961-1990) from high resolution regional climate model PRECIS (~50 km grid interval). According to climatic divisions of cropping systems in China, the active accumulated temperature stably passing the daily average temperature of 0°C, the extreme minimum temperature and the termination date passing the daily average temperature of 20°C which were justified by dominance as a limitation of different cropping systems in zero-grade zone were investigated. In addition, the possible trajectories of different cropping systems in China from 2011 to 2050 were also analyzed and assessed. Under the projected future B2 climate scenario, from 2011 to 2050, the northern boundaries of double cropping area and triple cropping area would move northward markedly. The most of the present double cropping area would be replaced by the different triple cropping patterns, while current double cropping area would shift towards areas presently dominated by single cropping systems. Thus the shift of multiple cropping areas would lead to a significant decrease of single cropping area. Compared with China’s land area, the percentage cover of single cropping area and double cropping area would decrease slowly, while percentage cover of triple cropping area would gradually increase.

Characteristics of Chemical Speciation in PM_(1)in Six Representative Regions in China

A better knowledge of aerosol properties is of great significance for elucidating the complex mechanisms behind frequently occurring haze pollution events.In this study,we examine the temporal and spatial variations in both PM_(1)and its major chemical constituents using three-year field measurements that were collected in six representative regions in China between 2012 and 2014.Our results show that both PM_(1)and its chemical compositions varied significantly in space and time,with high PM_(1)loadings mainly observed in the winter.By comparing chemical constituents between clean and polluted episodes,we find that the elevated PM_(1)mass concentration during pollution events should be largely attributable to significant increases in organic matter(OM)and inorganic aerosols like sulfate,nitrate,and ammonium(SNA),indicative of the critical role of primary emissions and secondary aerosols in elevating PM_(1)pollution levels.The ratios of PM_(1)/PM2.5 are found to be generally high in Shanghai and Guangzhou,while relatively low ratios are seen in Xi’an and Chengdu,indicating anthropogenic emissions were more likely to accumulate in forms of finer particles.With respect to the relative importance of chemical components and meteorological factors quantified via statistical modeling practices,we find that primary emissions and secondary aerosols were the two leading factors contributing to PM_(1)variations,though meteorological factors also played important roles in regulating the dispersion of atmospheric PM.

A New Statistic Approach towards Landslide Hazard Risk Assessment

To quantitatively assess the landslide hazard in Khelvachauri, Georgia, the statistic method of hazard index was applied. A spatial database was constructed in Geographic Information System (GIS) including topographic data, geologic maps, land-use, and active landslide events (extracted from the landslide inventory). After that, causal factors of landslides (such as slope, aspect, lithology, geomorphology, land-use and soil depth) were produced to calculate the corresponding weights, and thereby we defined a relevant set of spatial criteria for the latter landslide hazard assessment. On top of that, susceptibility assessment was performed in order to classify the area to low, moderate and high susceptible regions. Results showed that NW aspect, mountain geomorphology, private land-use, laterite loam and clay, slope between 19 to 24 degrees, and soil depth between 10 - 20 cm were found to have the largest contribution to high landslide susceptibility. The high success rate (72.35%) was obtained using area under the curve from the landslide susceptibility map. Meanwhile, effect analysis was carried out to assess the accuracy of the landslide susceptibility, indicating that the factor of slope played the most important role in determining the occurring probability of landslide although it did not deviate as much as other factors. Finally, the vulnerability analyses were carried out by means of the Spatial Multi-Criteria Estimation model, which in turn, led to the risk assessment. It turned out that not so much of the number of buildings (~ 34.13%) was associated with high-risk zone and that governmental and private land-use almost accounted for the same risk (39.9% and 40.9%, respectively).

Dinitrogen fixation mediated by lanthanum hydride

Dinitrogen fixation is one of the key reactions in chemistry, which is closely associated with food, environment, and energy. It has been recently recognized that the hydride materials containing negatively charged hydrogen(H~-) show promises for Nfixation and hydrogenation to ammonia. Herein, we report that rare earth metal hydrides such as lanthanum hydride can also fix Neither by heating to 200 °C or ball milling under ambient Npressure and temperature. The Nfixation by lanthanum hydride may proceed via an intermediate lanthanum hydride-nitride(La-H-N) structure to form the final lanthanum nitride product. The hydride ion functions as an electron donor, which provides electrons for Nactivation possibly mediated by the lanthanum atoms. It is observed that N–H bond is not formed during the Nfixation process, which is distinctly different from the alkali or alkaline earth metal hydrides. The hydrolysis of La-H-N to ammonia is feasible using water as the hydrogen source. These results provide new insights into the nitrogen fixation by hydride materials and more efforts are needed for the development of rare earth metal-based catalysts and/or nitrogen carriers for ammonia synthesis processes.

Estimation and Long-term Trend Analysis of Surface Solar Radiation in Antarctica: A Case Study of Zhongshan Station

Long-term,ground-based daily global solar radiation (DGSR) at Zhongshan Station in Antarctica can quantitatively reveal the basic characteristics of Earth’s surface radiation balance and validate satellite data for the Antarctic region.The fixed station was established in 1989,and conventional radiation observations started much later in 2008.In this study,a random forest (RF) model for estimating DGSR is developed using ground meteorological observation data,and a highprecision,long-term DGSR dataset is constructed.Then,the trend of DGSR from 1990 to 2019 at Zhongshan Station,Antarctica is analyzed.The RF model,which performs better than other models,shows a desirable performance of DGSR hindcast estimation with an R^2 of 0.984,root-mean-square error of 1.377 MJ m^(-2),and mean absolute error of 0.828 MJ m^(-2).The trend of DGSR annual anomalies increases during 1990–2004 and then begins to decrease after 2004.Note that the maximum value of annual anomalies occurs during approximately 2004/05 and is mainly related to the days with precipitation (especially those related to good weather during the polar day period) at this station.In addition to clouds and water vapor,bad weather conditions (such as snowfall,which can result in low visibility and then decreased sunshine duration and solar radiation) are the other major factors affecting solar radiation at this station.The high-precision,longterm estimated DGSR dataset enables further study and understanding of the role of Antarctica in global climate change and the interactions between snow,ice,and atmosphere.

Load Frequency Control of a Two Area-Power System with Non-reheat Turbines by SMC Approach

Load frequency is an important issue in power system operation and control. In this paper, load frequency control for suppression frequency deviation in an interconnected power system with nonlinearities using SMC （sliding mode control） is studied. The governor dead band and GRC （generation rate constraint） is considered in this article. Digit simulations for both two areas and three areas power system with non-reheat turbines are provided to validate the effectiveness of the proposed scheme. The results show that, the robustness of the control method under parameters variation and different load disturbances with the SMC technique.

Standards on the Bildegradability of Surfactants in China

This paper described general situation of surfactant production and waster water treatment in China, and introduced Chinese standards on chemical biodegradation. Furthermore, it summarized at three level of Chinese relevant standards. Finally, it explored in detail the particular differences between Chinese standards and OECD methods.

石墨烯在析氢电催化剂中的应用

氢能源是新能源技术发展的重要方向。工业化规模电解水制氢需要采用低成本析氢催化剂材料降低其过电势。石墨烯因其具有超大的比表面积、优异的导电性、良好的稳定性、可调的电子结构以及结构和表面态易于修饰等优点,在析氢电催化剂材料中展现出了广阔的应用前景。本文详细分析了石墨烯应用于析氢电催化中的作用机制。依据作用机制的不同,对石墨烯析氢电催化剂材料进行了分类,并对其研究进展进行了综述。最后对石墨烯析氢电催化材料的发展方向进行了展望。

多相化学合成氨研究进展

氨不仅是氮肥的主要原料,亦可作为能源载体在可再生能源的储存与转化过程中发挥重要的作用.而氨的化学合成是实现这一过程的关键.现有的Haber-Bosch合成氨工业是一个高能耗过程,开发温和条件下的合成氨过程是研究人员长期以来不懈追求的目标.随着催化科学与技术的进步,人们对合成氨微观反应机理的认识不断加深,这为进一步设计和开发低温高效的合成氨过程提供了许多有益的启示.本文分析了当前合成氨化学中的挑战与机遇,重点阐述了合成氨多相催化剂及化学链合成氨过程的开发,对近期发展迅速的电、光、等离子体等外场驱动的化学合成氨方面的研究进展也进行了简要介绍,强调了规避过渡金属上线性关系的限制是实现温和条件下合成氨的有效策略.

固氮反应中的凝聚态化学

氮是构成生命和物质世界不可或缺的元素,发展高效的转化方法将氮气分子转变为具有各种功能的含氮化合物,具有重要的经济价值和科学意义。氮气分子的活化转化是化学学科永恒的课题,而凝聚态化学的研究方法和多层面认识对固氮研究具有深刻意义。本文列举了一些固氮化学中的凝聚态现象,从均相溶液固氮、多相合成氨以及氮气/氧气多能耦合转化等三方面,讨论了目前固氮化学领域中存在的关键科学问题,期望启发更多学者从凝聚态化学角度思考固氮化学反应本质,为解决相关问题提供更多新的思路。

Assessment of the GPM and TRMM Precipitation Products Using the Rain Gauge Network over the Tibetan Plateau

Using high-quality hourly observations from national-level ground-based stations, the satellite-based rainfall products from both the Global Precipitation Measurement（GPM） Integrated Multisatellit E Retrievals for GPM（IMERG） and its predecessor, the Tropical Rainfall Measuring Mission（TRMM） Multi-satellite Precipitation Analysis（TMPA）, are statistically evaluated over the Tibetan Plateau（TP）, with an emphasis on the diurnal variation.The results indicate that：（1） the half-hourly IMERG rainfall product can explicitly describe the diurnal variation over the TP, but with discrepancies in the timing of the greatest precipitation intensity and an overestimation of the maximum rainfall intensity over the whole TP. In addition, the performance of IMERG on the hourly timescale, in terms of the correlation coefficient and relative bias, is different for regions with sea level height below or above 3500 m;（2） the IMERG products, having higher correlation and lower root-mean-square error, perform better than the TMPA products on the daily and monthly timescales; and（3） the detection ability of IMERG is superior to that of TMPA, as corroborated by a higher Hanssen and Kuipers score, a higher probability of detection, a lower false alarm ratio, and a lower bias. Compared to TMPA, the IMERG products ameliorate the overestimation across the TP. In conclusion,GPM IMERG is superior to TRMM TMPA over the TP on multiple timescales.