In the summer stratified water column , the deeper the maximum depth of food distribution is , the stronger the dvm is performed ; the increase of the gradient of temperature in the thermocline layer can decrease the magnitude of the dvm and form the thermal barricade to the copepod ; the effects of the predation pressure on dvm is complex . on the one hand , the variations in the distribution depth of the predation pressure vs . the thermocline layer or the depth of the maximum food can modify the dvm patterns of the copepod . on the other hand , different predation pressure induces different dvm patterns 在夏季分層水體中,食物的最大分布深度越大,動(dòng)物向下遷移的幅度也越大;溫躍層的溫度梯度增大可以減小動(dòng)物遷移的幅度,成為橈足類垂直遷移的溫度屏障;捕食壓力對(duì)垂直遷移的影響較復(fù)雜,一方面,捕食壓力的分布深度與溫躍層或食物峰值的相對(duì)位置的變化能夠改變橈足類垂直遷移的模式,另一方面,捕食壓力強(qiáng)度不同,橈足類垂直遷移的幅度也不同,捕食壓力越大,遷移的幅度越大,當(dāng)捕食壓力增加到一定程度,橈足類停止向上的遷移,大部分時(shí)間呆在水體深層,可能進(jìn)入捕食壓力引起的“滯育”狀態(tài)。
In the area of seasonal frozen region , the road takes place the cycle of freezing and thawing variety with the season , the mainly disease harm generating from this is the frost heave and frost boiling etc . . . the disease harm belongs to the heat transfer problem , but the effective measure to prevent and cure the frost boiling has something to do with the gradient of temperature and humidity 在季節(jié)性凍土地區(qū),道路隨季節(jié)交替發(fā)生凍融循環(huán)變化,由此產(chǎn)生的病害主要是凍脹和翻漿等。病害的形成歸根結(jié)底屬于熱質(zhì)遷移問(wèn)題,而防治凍脹與翻漿的有效措施無(wú)不與溫度和濕度有關(guān),搞清冬季凍結(jié)過(guò)程道路結(jié)構(gòu)體系溫度、濕度及應(yīng)力的狀況,是正確設(shè)計(jì)路基路面,防治凍脹和翻漿的先決條件。