低温固化高流平耐候型粉末涂料用聚酯树脂的制备与性能研究

为降低户外粉末涂料的固化温度,提升低温固化粉末涂料的流平性和耐候性,以1、6-己二醇(HDO)、新戊二醇(NPG)、三羟甲基乙烷(TME)、对苯二甲酸(TPA)、间苯二甲酸(IPA)为前驱体,通过本体聚合制备了低温固化高流平耐候型粉末涂料用聚酯树脂。研究了多元酸、多元醇和促进剂的种类和含量对聚酯树脂指标、粉末涂料性能的影响。采用红外光谱(FT-IR)、核磁共振波谱仪(^(1)H NMR)对聚酯树脂结构进行了表征;采用扫描电镜(SEM)对粉末涂料形貌进行观察。结果表明:当IPA、TME、HDO及促进剂含量分别为9%、0.4%、3%和2.5‰时制备的聚酯树脂综合性能较好;制备的粉末涂料经160℃/15 min低温固化,具有较好的机械性能、流平性、耐候性和耐腐蚀性;且低温固化的粉末涂料相结构均一,微观结构致密,层面附着力较好。

环保型高流平耐贮存粉末涂料用聚酯合成及性能研究

通过研究单官能度单体,使用PCDL和HBPA单体合成聚酯树脂,结果表明,SA用量为0.24%,PCDL为用量0.6%,HBPA用量为7.1%时,制备的羟烷基酰胺粉末涂料具有较好的机械性能、流平性能和贮存稳定性能。进一步使用固化抑制剂,使得制备的聚酯涂层具有优异的流平性能。

高流平性耐沾污内墙乳胶漆的研制

高流平性耐沾污内墙乳胶漆具有较好的流平性、耐沾污性和较低的成本。讨论了影响涂膜性能的因素并给出了该涂料的基本配方和技术性能。

高流平、耐沾污性内墙乳胶漆的研制

以聚乙烯醇为增稠流平剂及使用一种高分子蜡乳液制成的乳胶漆 ,改善了涂料的流平性和涂膜的憎水性。

一款环保型高流平低温轮毂底粉的制备及应用

介绍了一款环保型高流平铝合金轮毂底粉的配方设计、制备及应用。该粉末固化条件由传统的190℃×15 min降低到了150℃×20 min,较低的固化温度解决了现时铝轮毂制造企业普遍存在的因为底粉固化温度过高造成的轮毂刚性过剩、韧性不足的问题,使铝轮毂的刚性和韧性更趋向平衡,使用可靠性更高。同时固化温度的降低可以有效削减固化炉的能耗,更符合整个汽车行业节能环保的政策趋势。

户内平面用高流平β-羟烷基酰胺固化聚酯树脂的合成及应用研究

介绍了一种户内平面用高流平β-羟烷基酰胺(HAA)固化聚酯树脂的合成方法及其在粉末涂料涂层中表现。探讨了不同聚酯树脂的合成配方及工艺对于聚酯理化指标及涂层性能的影响,通过红外光谱(FITR)分析了聚酯的微观结构,利用凝胶渗透色谱仪(GPC)获得了一系列聚酯树脂的分子量及其分布,并通过扫描电子显微镜(SEM)观察了涂层的断面形貌。结果表明:n(EG)∶n(DEG)为2.774∶1,NPG占酯化醇物质的量比为55%,PTA作为酯化酸,ADA与IPA共同作为封端剂,其中ADA占单体总量1.8%(质量分数)时合成的聚酯树脂,其粉末涂层具有优异的流平性能和机械性能,50 kg·cm正、反冲击均可通过。

粉末涂料用HAA的合成及应用研究

在传统方法合成N,N,N',N',-四(β-羟乙基)己二酰胺(HAA)工艺的基础上,研究了催化剂种类、带甲醇用溶剂、结晶溶剂、烘干方式、外加剂对HAA产品及涂膜性能的影响。结果表明:在适宜的工艺条件下,HAA产品的纯度可以达到99%,并且可以实现较好的涂膜外观、厚膜针孔厚度及流平性。在保证产品纯度及膜厚、流平的基础上,外加干爽剂、厚膜针孔抑制剂也能进一步提高厚膜针孔的厚度及流平性,能够为高流平HAA粉末涂料的制备作参考。

Study on Epidemic Characteristics and Its Causes of Wheat Stripe Rust in Nanchong City

On basis of the research result of stripe rust for 16 years since 1999,the epidemic characteristics and trend of stripe rust in the city were determined.Namely,the earlier the initial stage appeared,the heavier the disease would be.Furthermore,stripe rust has two introduction infection peaks,of which the first peak plays a key role.In farmlands,there are one to three epidemic peaks,and the infection area of the first peak plays the key role on the epidemic area of that year.In addition,the accumulated areas of late January was in significantly positive correlation with annually total area,with a correlation coefficient of 0.769 2.In recent 16 years,the frequency of severe stripe rust was as high as 81.25% which was 50% higher than that before 1995.The slight stripe rust became just in 2013,with a frequency of 6.3%,which indicated that the city has become a region hit by severe stripe rust.The internal reason is the reduction or loss of wheat variety＇s resistance to tripe rust for a new physiological race of rust is becoming pathogenic stronger and be the major race.Big fluctuation of temperatures in warm winter and spring,foggy and dew days slants much would be the external reason.

Gaussian mixture models for clustering and classifying traffic flow in real-time for traffic operation and management

Based on Gaussian mixture models（GMM）, speed, flow and occupancy are used together in the cluster analysis of traffic flow data. Compared with other clustering and sorting techniques, as a structural model, the GMM is suitable for various kinds of traffic flow parameters. Gap statistics and domain knowledge of traffic flow are used to determine a proper number of clusters. The expectation-maximization （E-M） algorithm is used to estimate parameters of the GMM model. The clustered traffic flow pattems are then analyzed statistically and utilized for designing maximum likelihood classifiers for grouping real-time traffic flow data when new observations become available. Clustering analysis and pattern recognition can also be used to cluster and classify dynamic traffic flow patterns for freeway on-ramp and off-ramp weaving sections as well as for other facilities or things involving the concept of level of service, such as airports, parking lots, intersections, interrupted-flow pedestrian facilities, etc.

巴斯夫推出应用于100%固含量涂料的高效消泡剂

巴斯夫最近推出了Efka PB2744，它是针对100％固含量涂料系统的一种快速有效的消泡剂。它对大泡沫和小泡沫的消除都具有良好的效率、长期的持续性和有效性。它能提高在绝对应力和存储条件下的稳定性，同时也能提高流平性和表面平滑度。

NONPARALLEL BOUNDARY LAYER STABILITY IN HIGH SPEED FLOWS

The parabolized stability equations （PSEs） for high speed flows, especially supersonic and hypersonic flows, are derived and used to analyze the nonparallel boundary layer stability. The proposed numerical techniques for solving PSE include the following contents： introducing the efficiently normal transformation of the boundary layer, improving the computational accuracy by using a high-order differential scheme near the wall, employing the predictor-corrector and iterative approach to satisfy the important normalization condition, and implementing the stable spatial marching. Since the second mode dominates the growth of the disturbance in high Mach number flows, it is used in the computation. The evolution and characteristics of the boundary layer stability in the high speed flow are demonstrated in the examples. The effects of the nonparallelizm, the compressibility and the cooling wall on the stability are analyzed. And computational results are in good agreement with the relevant data.

Effects of 7.5% hypertonic saline on fluid balance after radical surgery for gastrointestinal carcinoma

AIM: To investigate the effects of 7.5% hypertonic saline on positive fluid balance and negative fluid balance, after radical surgery for gastrointestinal carcinoma. METHODS: Fifty-two patients with gastrointestinal carcinoma undergoing radical surgery were studied. The patients were assigned to receive either Ringer lactate solution following 4 mL/kg of 7.5% hypertonic saline (the experimental group, n = 26) or Ringer lactate solution (the control group, n = 26) during the early postoperative period in SICU. Fluid infusion volumes, urine outputs, fluid balance, body weight change, PaO2/FiO2 ratio, anal exhaust time as well as the incidence of complication and mortality were compared between the two groups. RESULTS: Urine outputs on the operative day and the first postoperative day in experimental group were significantly more than in control group (P<0.000001, P=0.000114). Fluid infusion volumes on the operative day and the first postoperative day were significantly less in experimental group than in control group (P= 0.000042, P= 0.000415). The volumes of the positive fluid balance on the operative day and during the first 48 h after surgery, in experimental group, were significantly less than in control group (P<0.000001). Body weight gain post-surgery was significantly lower in experimental group than in control group (P<0.000001). The body weight fall in experimental group occurred earlier than in control group (P<0.000001). PaO2/FiO2 ratio after surgery was higher in experimental group than in control group (P= 0.000111). The postoperative anal exhaust time in experimental group was earlier than in control group (P= 0.000006). The overall incidence of complications and the incidence of pulmonary infection were lower in experimental group than in control group (P= 0.0175, P= 0.0374). CONCLUSION: 7.5% hypertonic saline has an intense diuretic effect and causes mobilization of the retained fluid, which could reduce fluid infusion volumes and positive fluid balance after radical surgery for gastrointestinal carcinoma, as well as, accelerate the early appearance of negative fluid balance after the surgery, improve the oxygen diffusing capacity of the patients' alveoli, and lower the overall incidence of complications and pulmonary infection after the surgery.

The Kuroshio Transport East of Taiwan and the Sea Surface Height Anomaly from the Interior Ocean

The relationship between the Kuroshio transport to the east of Taiwan and the SSHA (Sea Surface Height Anomaly) field is studied based on the World Ocean Circulation Experiment (WOCE) PCM-1 moored current meter array observation, the satellite altimeter data from the MSLA (Map of Sea Level Anomaly) products merged with the ERS and TOPEX/POSEIDON (T/P) data sets, and the WOCE satellite-tracked drifting buoy data. It is confirmed that the Kuroshio transport across PCM-1 array highly correlates with the SSHA upstream (22°-24°N, 121.75°-124°E). The SSHA is not locally generated by the developed Kuroshio meandering but is from the interior ocean and is propagating westward or northwestward. During the period from October 1992 to January 1998, two events of the northwestward propagating negative SSHA occurred, during which the SSHA merged into the Kuroshio and caused the remarkable low transport events in contrast to the normal westward propagating negative SSHA. It is also shown that the lower Kuroshio transport event would be generated in different ways. The negative anomaly in the upstream of PCM-1 array can reduce the Kuroshio transport by either offshore or onshore Kuroshio meandering. The positive anomaly, which is strong enough to detour the Kuroshio, can cause an offshore meandering and a low transport event at the PCM-1 array.

STRUCTURE OF SOUTH ASIA HIGH IN THE STRATOSPHERE AND INFLUENCE OF ENSO

The structure of the South Asia High(SAH)in the stratosphere and the influence of ENSO on the SAH are systematically investigated with the long-term ECMWF reanalysis data.The results show that the SAH only exists in low levels of the stratosphere.The maximum intensity of the High is located at around 150 hPa and there is no obvious anti-cyclonic structure above 50 hPa.The axis of the SAH center tends to be northwest slanting from lower levels to higher levels.Further analyses show that the geopotential height and temperature fields of the SAH have dramatic anomalies during El Ni?o years and La Ni?a years. Corresponding to the ENSO,the SAH is weaker(stronger)at the warm(cold)phase.

A modified method to estimate eddy diffusivity in the North Pacific using altimeter eddy statistics

The method proposed by Stammer (1998) is modified using eddy statistics from altimeter observation to obtain more realistic eddy diffusivity (K) for the North Pacific. Compared with original estimates, the modified K has remarkably reduced values in the Kuroshio Extension (KE) and North Equatorial Counter Current (NECC) regions, but slightly enhanced values in the Subtropical Counter Current (STCC) region. In strong eastward flow areas like the KE and NECC, owing to a large difference between mean flow velocity and propagation velocity of mesoscale eddies, tracers inside the mesoscale eddies are transported outside rapidly by advection, and mixing length L is hence strongly suppressed. The low eddy probability (P) is also responsible for the reduced K in the NECC area. In the STCC region, however, L is mildly suppressed and P is very high, so K there is enhanced. The zonally-averaged K has two peaks with comparable magnitudes, in the latitude bands of the STCC and KE. In the core of KE, because of the reduced values of P and L, the zonally-averaged K is a minimum. Zonally-integrated eddy heat transport in the KE band, calculated based on the modified K, is much closer to the results of previous independent research, indicating the robustness of our modified K. The map of modified K provides useful information for modeling studies in the North Pacific.

Rarefied planar jets into vacuum

This paper presents a fundamental gaskinetic study on high speed rarefied jets expanding into vacuum from a cluster of planar exits.Based on the corresponding exact expressions for one planar jet,this paper straightforwardly derives the combined multiple jet flowfield solutions of density and velocity components,however,for the combined temperature and pressure solutions,extra attention shall be practiced.Several direct simulation Monte Carlo simulation results are provided and they validate these analytical solutions of rarefied planar jet flows.

Joint effects of three oceans on the 2020 super mei-yu

An unexpected super mei-yu struck in 2020 in the Yangtze-Huaihe River basin,southern Korea,and southern Japan(hereafter referred to as the mei-yu regions),causing many casualties and huge economic losses.The super mei-yu was characterized by a remarkably early onset(around 1 June),late withdrawal(around 1 August),and intense rainfalI during the mei-yu season.The precipitation in the early onset and late withdrawal stages contributed more than half of the total mei-yu-period precipitation over the mei-yu regions in 2020.In this study,the authors explored the dominant remote forcing of the mei-yu early onset and late withdrawal to understand the mechanisms of this super mei-yu.The early onset can mainly be attributed to an early northward-shifted East Asian jet stream(EAJS).The late withdrawal mainly resulted from the stagnant EAJS and the western North Pacific subtropical high(WPSH) during 10 July to 1 August.Specifically,North Atlantic sea surface temperature anomalies(SSTAs) excited a Rossby wave,which was steered by atmospheric anomalies related to the western North Pacific SSTAs,causing the early northward-shifted EAJS and generating an early onset.The record-breaking warm SSTAs over the North Indian Ocean to South China Sea and the reduced sea-ice concentration(SIC) over the Laptev-East Siberian Sea played important roles in causing the stagnant WPSH and EAJS during July,which led to the late withdrawal.Meanwhile,the SIC anomalies may have caused the inhomogeneous rainfall distribution in the mei-yu regions.Furthermore,projection results suggest that the probability of a late mei-yu withdrawal similar to the 2020 case will increase in the future.Finally,potential predictors of an extreme mei-yu are discussed.

Subsurface temperature anomalies in the North Pacific Ocean associated with the ENSO cycle

Multi-year Simple Ocean Data Assimilation （SODA） and National Centers for Environmental Prediction （NCEP） datasets were used to investigate the leading patterns of subsurface ocean temperature anomalies （SOTA） and the corresponding atmospheric circulation structure in the Pacific Ocean （20°S-60°N）. In this paper, the evolution of North Pacific SOTA associated with El Nifio-southern oscillation （ENSO）, and their relationship with the overlying zonal/meridional atmospheric circulations were elucidated. The results indicate that： （1） there are two dominant modes for the interannual variability of the North Pacific SOTA. The primary mode is the dipole pattern of the central and western North Pacific SOTA associated with the leading mode of ENSO, and the second mode is the zonal pattern related to the second mode of ENSO. These two modes consist of the temporal-spatial variation of the SOTA in the North Pacific. （2） During the developing phase of the El Nifio event, positive （negative） SOTA appears in the western （central） portion of the North Pacific Ocean. During the mature and decaying phase of the E1 Nifio event, the western positive center and the central negative center continue to be maintained and enhanced. Meanwhile, the position of the western positive center slightly changes, and the central negative center moves eastward slowly. After the El Nifio event vanishes, the positive SOTA disappears, and the central negative SOTA becomes weak and remains in the northeastern Pacific Ocean. The results for La Nifia are generally the opposite. （3） During the El Nifio/La Nifia cycle, formation and evolution of the SOTA, with opposite signs in central and western North Pacific Ocean, resulted from vertical movement of the two northern branches of the Hadley Cell with opposite direction, as well as the positive feedback of the air-sea interaction induced by dynamic processes in the mid-latitudes. The former gives rise to the initial SOTA, and the latter intensifies SOTA. Under the forcing of these two processes, SOTA evolution is formed and sustained during the El Nino/La Nina events. Also discussed herein as background for the ENSO cycle are the possible connections among the West Pacific subtropical high, the strength of the Kuroshio near the East China Sea, the Kuroshio meanders south of Japan, the Aleutian Low, and cold advection in the central North Pacific Ocean.