An experience of tunnelling in mudstone area in southwestern Taiwan

Many tunnels will be constructed in southwestern Taiwan in the upcoming decade to meet the huge demands of transportation, energy and water infrastructure projects. Mudstone strata cover more than a 1000 km² area, consisting mainly of massive mudstone or alternation of mudstone and sandy layer, exhibiting unfavorable geological and hydrological characteristics, making it extremely difficult for tunnelling. This paper presents the lessons learned from three tunnelling projects in the 1990s in a mudstone area. In addition to discussing the rock behavior in the vicinity of tunnel and its failure patterns, the monitoring data during tunnelling are presented as well. Finally, the effective method of design and construction are recommended for tunnelling in mudstone area.     

考虑抗力退化的公路钢筋混凝土梁抗弯强度可靠性分析

本文采用了一个时变荷载模型和一个考虑了钢筋锈蚀，钢筋屈服拉力，混凝土抗压强度和粘结力等多个影响因素的多参数抗力劣化模型，对公路钢筋混凝土梁抗弯强度可靠性在服役期内的变化趋势进行了研究，并针对一实例对各影响参数对可靠性分析的敏感性进行了分析。     

Physiological deterioration of cassava roots

Rapid post-harvest physiological deterioration of cassava roots (Manihot esculenta Crantz) appears to be due essentially to wound responses, comparable to those observed in other plant storage organs. The wound responses observed include: increased activity of phenylalanine ammonia lyase, an enzyme associated with phenol biosynthesis; increased activity of peroxidase and polyphenol oxidase; formation of phenols/polyphenols including leucoanthocyanidins, catechins, sco-poletin and condensed tannins, and often the formation of a wound periderm. In cassava, the responses did not remain localised at wound surfaces in roots when held at low storage humidity but spread through the roots causing a discolouration of the vascular tissue and storage parenchyma. Roots stored at high humidity showed a more typical wound response with localised production of phenols and periderm formation.     

Mannitol and oligosaccharides as new criteria for determining cold tolerance in sugarcane varieties

Sugarcane can be very susceptible to damage by freezes. Freeze-deteriorated cane can cause problems in processing and sometimes leads to a factory shut-down. This study was undertaken during the 2000/2001 harvest season to assess the cold tolerance performance of six commercial sugarcane varieties and to establish new and more sensitive criteria to measure cold tolerance. Two varieties CP 70-321 and CP 79-318, with known cold tolerance, were planted in the study as controls. The other varieties included LHo 83-153, LCP 85-384, HoCP 85-845 and HoCP 91-555. Freezing temperatures occurred on 20 December 2000 when the min. field temperature was −4.4 °C, and again on 21 December, 30 December through 5 January 2001, 9–10 January and 20–21 January. The lowest field temperature recorded was −5.6 °C on 4 January. Freezing conditions prevailed for 8–15 h during each freeze incident. Stalks of all varieties were frozen to the ground following the initial freeze, with freeze cracks evident only after the 4 January freeze. For this study, samples were taken on the date of the first freeze, 20 December, and subsequently again at 7, 14, 22 and 30 days after the first freeze. Criteria used to measure overall stalk cold-tolerance included changes in pH, Brix, dextran (ASI-II method), sucrose, glucose, and fructose concentrations. Mannitol, ethanol and the oligosaccharides, palatinose, leucrose, iso-maltotriose and 1-kestose, were simultaneuously measured using IC-IPAD. Marked differences were observed in most criteria for all varieties, particularly 22 and 30 days after the first freeze. Mannitol was strongly correlated (r²=0.84) with dextran, confirming its use as an indicator for cane dextran deterioration. In comparison, ethanol was only weakly correlated (r²=0.55) with dextran and did not always predict cane dextran deterioration. Iso maltotriose was the most sensitive oligosaccharide indicator of freeze deterioration, although both leucrose and palatinose could be used to confirm whether severe dextran formation (>1500 ppm/Brix) has occurred in cane. Isomaltotriose was strongly correlated (r²=0.89) with dextran and pH (r²=−0.83); pH was also a strong indicator of both dextran (r²=−0.85) and mannitol (r²=−0.92) formation. Four of the varieties, CP 79-318, LCP 85-384, HoCP 85-845 and HoCP 91-555, were shown to be susceptible to other sources of microbial and enzymic deterioration as well as dextran deterioration from Leuconostoc bacteria, especially 30 days after the first freeze. This was indicated by increased glucose/fructose ratios, ethanol formation, changes in 1-kestose concentration, and further sucrose losses.     

Axial characterization of catalytic activity in close-coupled lightoff and underfloor catalytic converters

A exhaust system consisting of a close-coupled Pd technology 32 in³ lightoff converter and Pt/Rh technology 170 in³ underfloor converter was vehicle-aged for 56000 miles on a vehicle equipped with a 3.8 l engine. Following this aging, the converters were taken off the vehicle and cut into 1″ thick sections along their axis and characterized for lightoff and warmed-up activity using a laboratory reactor to simulate vehicle exhaust. Each section was also analyzed for the quantity of oil additive poisons (phosphorus and zinc) deposited. Following this initial characterization, the phosphorus and zinc deposits were removed, and the sections were characterized again for lightoff and warmed-up activity. This procedure was used to qualitatively determine the relative contribution of oil additive poisoning and thermal sintering to the total activity deterioration as a function of axial position in the catalyst monoliths.

Analysis of the lightoff converter as taken from the vehicle showed a dramatic axial gradient in the lean and stoichiometric lightoff and warmed-up (600°C) performance for HC, CO and NO_x, with most of the deterioration having taken place in the forward-most 1″ section of the converter, which was consistent with the gradient in the deposition of phosphorus (P) and zinc (Zn) in this converter. Comparison of these data sets with those obtained after removal of the P and Zn poisons indicates that most of the total deterioration of lean HC and CO activity can be attributed to P and Zn poisoning of the forwardmost 1″ section. When tested under stoichiometric conditions, most of the deterioration of HC activity is attributable to P and Zn poisoning, while most of the deterioration of CO and NO_x activity is attributable to thermal deterioration. A similar activity and poison deposition gradient was detected in the underfloor converter, but to a smaller extent.     

拱桥吊杆的常见病害分析

重点分析了拱桥吊杆的常见病害类型如：锚头部位病害、护套病害、吊杆索体病害,其中索体的钢丝锈蚀是降低吊杆承载能力和使用寿命的直接原因。在分析各种病害成因的基础上提出了改善措施来减小吊杆的病害。     

Tactical combat movements: inter-individual variation in performance due to the effects of load carriage

An examination into the effects of carried military equipment on the performance of two tactical combat movement simulations was conducted. Nineteen Airfield Defence Guards performed a break contact (five 30-m sprints) and a fire and movement simulation (16 6-m bounds) in five load conditions (10–30 kg). Heavier loads significantly increased movement duration on the break contact (0.8%/kg load) and fire and movement (1.1%/kg). Performance deterioration was observed from the beginning to the end of the series of movements (bounds or sprints) with deterioration becoming significantly greater in heavier load conditions. Inter-individual variation between slower and faster participants showed a range in load effects; 0.6, 0.8%/kg for fast and 1.0, 1.4%/kg for slow (break contact, fire and movement, respectively). Velocity profiles revealed that the initial acceleration and peak velocity were the primary determinants of performance. As the duration of these tactical combat movements reflects periods of heightened vulnerability, these findings highlight important implications for commanders.

Practitioner Summary: Increasing amounts of carried military equipment impairs the performance of tactical combat movements. Examination of inter-individual variation in velocity profiles identified that the initial acceleration and the peak velocity achieved during sprints and bounds are key determinants of overall performance.     

阀控式铅酸蓄电池正极板劣化模式分析

对于阀控式铅酸蓄电池而言 ,除了制造过程中产生的缺陷以外 ,正极板劣化是其寿命终止的主要原因之一。本文将从板栅、活物质、电解液以及他们之间的相互关系等角度出发 ,对阀控式铅酸蓄电池的正极板劣化模式进行了详细的论述 ,并针对不同的劣化原因提出了相应的改善方法。     

2×2稠密棒束内超临界水的传热特性试验研究

在压力p=23～28 MPa、质量流速G=350～1 000 kg/(m²•s)、热流密度q=200～1000 kW/m²的试验参数范围内,对2×2棒束内超临界水的传热特性进行了试验研究。试验得到了加热管周向壁温分布规律,并就出现周向温度差异的原因进行了分析。此外,给出了压力、质量流速及热流密度等系统参数对平均传热特性的影响,分析了低质量流速下出现的传热恶化现象。试验结果表明：加热管周向壁温并不均匀,边角子通道壁温最高,中心子通道壁温最低,周向壁温的高低与横截面流通面积的不均匀性紧密相关。随着热流密度的提高或质量流速的降低,超临界水的传热受到抑制,当q/G增大到一定程度时,棒束内发生传热恶化。     

劣化导热油的离心沉降处理探索

采用离心沉降方法处理受到粗对苯二甲酸（TA）污染和劣化的加氢精制系统导热油,对离心沉降时间、离心沉降转速等工艺条件对导热油的固体杂质和胶质含量、酸值的影响进行了讨论,确定了最佳的工艺条件,试验结果表明离心沉降的处理方法可以显著降低导热油中的固体杂质和胶质含量及酸值。