汽轮机轴向位移保护装置起什么作用？有哪几种型式？
参考答案：
汽轮机转子与静子之间的轴向间隙很小，当转子的轴向推力过大，致使推力轴承乌金熔化时，转子将产生不允许的轴向位移，造成动静部分摩擦，导致设备严重损坏事故，因此汽轮机都装有轴向位移保护装置。其作用是：当轴向位移达到一定数值时，发出报警信号；当轴向位移达到危险值时，保护装置动作，切断进汽，停机。
轴向位移保护装置按其感受元件结构，可分为机械式、液压式、电气式三大类。前面两类常用于中小型汽轮机上，后者都用于大功率汽轮机上。
根据短文内容，从下框的A-F选项中选出能概括每一段主题的最佳选项。选项中有一项为多余项。
Sonja Lyubomirsky, an author, has researched the science of happiness for years． Here are her tips to help you cope with a bad economy, and increase your bursts of happiness throughout the day． 小题1:________ “You could spend a lot of time thinking deeply,” says Lyubomirsky．“But that just makes you feel even more pessimistic, more out of control, and affects your self esteem．Your relationships will suffer and your job performance will suffer．” Get rid of pessimism．One of the most effective ways to cope when things are difficult is to adopt a positive thinking strategy．“What can I learn from this? Times are tough, I’ve been furloughed at work, but I can spend more time with the kids, adopt a new hobby, or learn a new set of skills．” 小题2:________ Now more than ever we need each other to survive．Lyubomirsky found that doing good things for friends, family, or strangers can make you happier．Think of practical, everyday gestures that can make someone’s life a little bit easier．For example, Lyubomirsky says, “Maybe now many of us can’t afford to take a cab to the airport, so offer to give a friend a ride．” 小题3:________ You don’t need an expert to tell you that relationships are critical to happiness． Not being the bread-winner anymore or not being able to fulfill your kid’s needs can weigh down hard on your family life．But the trick is to stop feeling guilty and focus on caring for your loved ones． “I was at a psychology conference where an expert was talking about the effects of this economy on families and how parents can’t afford to buy their kids luxuries like toys anymore,” says Lyubomirsky．“But what they don’t realize is that kids don’t care about toys — what they care about is parents being grumpy and taking it out on them．” 小题4:________ “If you find a happy person you will find a project,” says Lyubomirsky．“Happy people all have goals they care about．” Commit yourself to a project – whether it is a business you want to start or a dance you want to learn．But it’s also important to remember to be flexible in these times． Don’t get frustrated if circumstances are stopping you from meeting your goals．Adopt and change! “If your spouse has lost their job you might have to change your goal,” says Lyubomirsky．“Or you might have to learn a whole new skill for a new job．” 小题5:________ When times are tough, it’s easy to get skip your regular workouts in favor of moping in front of the TV and eating a bag of chips．Your thinking is “I have more important things to worry about right now than looking good．” But carve out a small part of your day to give your body some TLC．It will go a long way in boosting your happiness．“Even if you can’t afford to go to the gym,” Lyubomirsky says, “take time out to exercise at home．” |