我国古代航海用的几种水时计

一、沉碗型水时计的椰子壳泉州古船出土遗物,有一颗完整的椰子壳,和椰子壳残片,共十三件,分布在第二舱一件,第三舱二件,第六舱七件,第十一舱三件,以上都是残件,只有出土于第十三舱那一件才是完整椰子壳,其壳顶开一小孔,直径约4.7厘米。距离壳顶这个小孔之下,约有2.8厘米,又有一个小孔,直径仅0.8厘米,它的高度为10.5厘米。椰子壳腹部外面的直径,约为16.5厘米。腹部内面的直径。神为15.6厘米。

船用水时计及泉州出土椰壳等讨论

我国东南面临大海,有着长达万里的海岸线。早在两千多年以前,我国的航海事业就很发达。《淮南子·齐俗训》中说,"夫乘舟而惑者不知东西,见斗、极则寤矣"。说明在茫茫大海上航行,观察星象以保持正确航向的重要性。为了辨别方向,指南针、牵星术等在航海中得到广泛应用。为了计算时间和航程,计时仪器也在船舶上得到应用。据文献记载,中国古代船舶中使用的计时仪器,主要有水时计(刻漏)、火时计两大类。此外还有沙漏。本文主要讨论水时计及泉州出土宋船上的椰壳等有关问题。

Internal Loads and Bioavailability of Phosphorus and Nitrogen in Dianchi Lake,China

Sediments have a significant influence on the cycling of nutrient elements in lake environments. In order to assess the distribution characteristics and estimate the bioavailability of phosphorus and nitrogen in Dianchi Lake, organic and inorganic phosphorus and nitrogen forms were analysed. The 210 Pb radiometric dating method was employed to study temporal changes in the phosphorus and nitrogen pools in Dianchi Lake. The result show that the total phosphorus(TP) and total nitrogen(TN) were both at high concentrations, ranging from 697.5–3210.0 mg/kg and 1263.7–7155.2 mg/kg, respectively. Inorganic phosphorus(IP) and total organic nitrogen(TON) were the main constituents, at percentages of 59%–78% and 74%–95%, respectively, in the sediments. Spatially, there was a decreasing trend in phosphorus and nitrogen contents from the south and north to the lake centre, which is related to the distribution pattern of local economic production. The burial rates of the various phosphorus and nitrogen forms increased in same spatially and over time. Particularly in the past two decades, the burial rates doubled, with that TN reached to 1.287 mg/(cm^2·yr) in 2014. As the most reactive forms, nitrate nitrogen(NO_3-N) and ammonia nitrogen(NH_4-N) were buried more rapidly in the south region, implying that the potential for releasing sedimentary nitrogen increased from north to south. Based on their concentrations and burial rates, the internal loads of phosphorus and nitrogen were analysed for the last century. A TP pool of 71597.6 t and a TN pool of 81191.7 t were estimated for Dianchi Lake. Bioavailable phosphorus and nitrogen pools were also estimated at 44468.0 t and 5429.7 t, respectively, for the last century.

Application of Multivariate Model Based on Three Simulated Sensors for Water Quality Variables Estimation in Shitoukoumen Reservoir,Jilin Province,China

This study applied a multivariate model based on three simulated sensors to estimating water quality variables in Shitoukoumen Reservoir,Changchun City,Jilin Province,China,including concentration of total suspended matter,concentration of chlorophyll-a and non-pigment matter absorption.Two field campaigns for spectra measurements with a total of 40 samples were carried out on June 13 and September 23,2008.The in-situ spectra were recalculated to the spectral bands and sensitivities of the instruments applied in this paper,i.e.Landsat TM,Alos and P6,by using the average method.And the recalculated spectra were used for estimating water quality variables by the single model and multivariate model.The results show that the multivariate model is superior to the single model as the multivariate model takes the combined effects of water components into consideration and can estimate water quality variables simultaneously.According to R2 and RMSE,Alos is superior to other sensors for water quality variables estimation although the precision of non-pigment matter absorption inversion performed the second.

Analysis of Runoff in Ungauged Mountain Watersheds in Sichuan,China using Kinematic-wave-based GIUH Model

Floods are one of the most common natural hazards occurring all around the world.However,the knowledge of the origins of a food and its possible magnitude in a given region remains unclear yet.This lack of understanding is particularly acute in mountainous regions with large degrees in Sichuan Province,China,where runoff is seldom measured.The nature of streamflow in a region is related to the time and spatial distribution of rainfall quantity and watershed geomorphology.The geomorphologic characteristics are the channel network and surrounding landscape which transform the rainfall input into an output hydrograph at the outlet of the watershed.With the given geomorphologic properties of the watershed,theoretically the hydrological response function can be determined hydraulically without using any recorded data of past rainfall or runoff events.In this study,a kinematic-wave-based geomorphologic instantaneous unit hydrograph (KW-GIUH) model was adopted and verified to estimate runoff in ungauged areas.Two mountain watersheds,the Yingjing River watershed and Tianquan River watershed in Sichuan were selected as study sites.The geomorphologic factors of the two watersheds were obtained by using a digital elevation model (DEM) based on the topographic database obtained from the Shuttle Radar Topography Mission of US's NASA.The tests of the model on the two watersheds were performed both at gauged and ungauged sites.Comparison between the simulated and observed hydrographs for a number of rainstorms at the gauged sites indicated the potential of the KW-GIUH model as a useful tool for runoff analysis in these regions.Moreover,to simulate possible concentrated rainstorms that could result in serious flooding in these areas,synthetic rainfall hyetographs were adopted as input to the KW-GIUH model to obtain the flow hydrographs at two ungauged sites for different return period conditions.Hydroeconomic analysis can be performed in the future to select the optimum design return period for determining the flood control work.

The influence of anoxia design and change aerations time on the treatment from coke plant wastewater

According to a great deal of experimental findings and the oretical analysis, theperformance of SBR process treating organic substance and ammonia was presented for different operating pattern and aeration time.When the operation mode is feeding water,anoxie mixing 2.5 h, settlement, and draining for 1.5 h, the coke plant wastewater can be treated well by the SBR method.

Rainfall and Obtaining Information Regarding Earthquake Development Processes from Groundwater Level

Many factors can cause changes of groundwater level,such as the development process of an earthquake,rainfall,solid earth tides etc.Among these we are interested in information regarding earthquake development processes.Eliminating the influence of various disturbance factors is an effective way to obtain seismic development process information contained in the groundwater level.This paper provides two different ways to remove the rainfall effect,and compares the two methods by means of correlation analysis.Furthermore,based on these a logistic regression model is established to describe the seismicity level.

The Model Research on the Flooding Time of the Warship Damaged Compartment

Research on damage stability and unsinkability is a valuable source of knowledge of behaving a ship while flooding its compartments. The time when compartment is flooded （ty） and stability parameters are key elements which have influence on a rescue action. The knowledge of the time mentioned is very important for a commanding officer to make decisions while fighting for survival of the ship. Therefore, the purpose of research was to develop a method to accurately and quickly calculate the flooding time of selected ship compartment. To provide the information about the time ty, a new method was designed. This method was based on an accurate determination of the amount of water entering to the compartment. For this purpose, the permeability depends on the water level in the compartment. Next, the computer program was built for both the time tfcalculation and showing the flooding process. This method was tested experimentally and the results of the tests are presented in the paper. In the next part of research, which was carried out on the laboratory stand bed, the flooding time of damaged compartment of warship model was measured. The results of calculation are compared to the experiments and discussed.

Time-domain CFD computation and analysis of acoustic attenuation performance of water-filled silencers

The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies.

A Nonlinear Vortex Induced Vibration Model of Marine Risers

With the exploitation of oil and gas in deep water, the traditional vortex induced vibration (VIV) theory is challenged by the unprecedented flexibility of risers. A nonlinear time-dependent VIV model is developed in this paper based on a VIV lift force model and the Morison equation. Both the inline vibration induced by the flow due to vortex shedding and the fluid-structure interaction in the transverse direction are included in the model. One of the characteristics of the model is the response-dependent lift force with nonlinear damping, which is different from other VIV models. The calculations show that the model can well describe the VIV of deepwater risers with the results agreeing with those calculated by other models.

Irrigation Management in Real Time for Arugula Crop in Sergipe

The management of the irrigation is fundamental for success of leaves vegetables production. The work was carried out aiming to evaluate the production response of the arugula （Eruca sativa Mill.） under different irrigation levels at 25, 31, 37 and 43 days after sowing. The treatments were distributed in randomized blocks design with four replication, and evaluated in split-plot scheme of 4 × 4, with the plots constituted by four irrigation levels equivalent to reference evapotranspiration （ET0） at 50%, 75%, 100% and 125% estimated by Penman-Monteith equation; and the split-plot constituted by days after sowing. The arugula planting was established in November of 2008 with direct sowing in nursery with 0.1 m × 0.2 m per plant, using the cv. ＂Folha Larga＂. After the germination phase was carried out crop management necessary to the crop production. It was analyzed： plant height （cm）, leaf number, fresh weight （g m2） and dry weight （g m2）. The results showed the significant differences at level of 5% of probability for the Scott-Knott test for all variables analyzed after 37 days of planting. The results permit to infer that the irrigation levels exert influence under the studied variables with the higher efficiency of water use found for levels of 75% and 100% of the reference evapotranspiration.

Simultaneous estimation of soil moisture and hydraulic parameters using residual resampling particle filter

Land data assimilation(DA) has gradually developed into an important earth science research method because of its ability to combine model simulations and observations.Integrating new observations into a land surface model by the DA method can correct the predicted trajectory of the model and thus,improve the accuracy of state variables.It can also reduce uncertainties in the model by estimating some model parameters simultaneously.Among the various DA methods,the particle filter is free from the constraints of linear models and Gaussian error distributions,and can be applicable to any nonlinear and non-Gaussian state-space model;therefore,its importance in land data assimilation research has increased.In this study,a DA scheme was developed based on the residual resampling particle filter.Microwave brightness temperatures were assimilated into the macro-scale semi-distributed variance infiltration capacity model to estimate the surface soil moisture and three hydraulic parameters simultaneously.Finally,to verify the scheme,a series of comparative experiments was performed with experimental data obtained during the Soil Moisture Experiment of 2004 in Arizona.The results show that the scheme can improve the accuracy of soil moisture estimations significantly.In addition,the three hydraulic parameters were also well estimated,demonstrating the effectiveness of the DA scheme.

Aggregation-induced emission and thermally activated delayed fluorescence of 2,6-diaminobenzophenones

Exploration of novel organic luminophores that exhibit thermally activated delayed fluorescence(TADF) in the aggregated state is very crucial for advance of delayed luminescence-based applications such as time-gated bio-sensing and temperature sensing.We report herein that synthesis, photophysical properties, molecular and crystal structures, and theoretical calculations of 2,6-bis(diarylamino)benzophenones. Absorption spectra in solution and calculations using density functional theory(DFT) method revealed that the optical excitation took place through intramolecular charge-transfer from one diarylamino moiety to an aroyl group. While the benzophenones did not luminesce in solution, the solids of the benzophenones emitted green light with moderate-to-good quantum yields. Thus, the benzophenones exhibit aggregation-induced emission. Based on the lifetime measurement, the green emission of the solids was found to include TADF. The emergence of the TADF is supported by the small energy gap between the excited singlet and triplet states, which was estimated by time-dependent DFT calculations. Thin films of poly(methyl methacrylate) doped by the benzophenones also showed green prompt and delayed fluorescence whose lifetimes were in the order of microseconds. Linear correlation between logarithm value of TADF lifetime and temperature was observed with the benzophenone in powder, suggesting that the benzophenones can serve as molecular thermometers workable under aqueous conditions.

Calculation of fire extinguishment time with water mist in an enclosed room

The fire extinguishment time is a major factor to evaluate the efficiency of fire extinguishment with water mist. In this paper the fire extinguishment time with water mist in an enclosed room is calculated. Before adding water mist, the chemical kinetics plays the role in combustion, where a dimensionless math model is established by us-ing the Semenov theory. After adding water mist, the diffusion plays the role instead. Then another math model containing water mist and dominated by oxygen concentration is established. The fire temperature is integrated from Tm to extinguishment temperature TB and the extinguishment time can be obtained. The calculated values are compared with the experimental data under different conditions. The results show that this model can predict the fire extinguishment time accurately. Besides, this model also can be used to determine the critical water mist flux and evaluate which fire extinguishment mechanisms dominate the extinguishment.