超声面积测量英文

一、1）磁粉探伤的英文简称是MT；2）超声波检测的英文简称是UT。二、1）磁粉探伤A）定义：有表面或近表面缺陷的工件被磁化后，当缺陷方向与磁场方向成一定角度时，由于缺陷处的磁导率的变化，磁力线逸出工件表面，产生漏磁场，吸附磁粉形成磁痕。B）磁粉探伤原理：a.首先将被检焊缝局部充磁，焊缝中便有磁力线通过。b.对于断面尺寸相同、内部材料均匀的焊缝，磁力线的分布是均匀的。c.当焊缝内部或表面有裂纹、气孔、夹渣等缺陷时，磁力线将绕过磁阻较大的缺陷产生弯曲。d.此时在焊缝表面撒上磁粉，磁力线将穿过表面缺陷上的磁粉，形成“漏磁”。根据被吸附磁粉的形状、数量、厚薄程度，便可判断缺陷的大小和位置。1）超声波检测A）超声波检测的定义：通过超声波与试件相互作用，就反射、透射和散射的波进行研究，对试件进行宏观缺陷监测、几何特性测量、组织结构和力学性能变化的检测和表征，并进而对其特定应用性进行评价的技术。 B）超声波工作的原理：主要是基于超声波在试件中的传播特性。a.声源产生超声波，采用一定的方式使超声波进入试件；b.超声波在试件中传播并与试件材料以及其中的缺陷相互作用，使其传播方向或特征被改变；c.改变后的超声波通过检测设备被接收，并可对其进行处理和分析；d.根据接收的超声波的特征，评估试件本身及其内部是否存在缺陷及缺陷的特性。

Ultrasound Ultrasound is a technique that uses sound waves to show a picture of a baby (fetus) in the uterus. Because it uses sound waves instead of radiation, ultrasound is safer than X-rays. Ultrasound provides important information about the health of the fetus and conditions in the uterus. This information can guide a health care provider's plans for a pregnant woman and improve the outcome of pregnancy. How does ultrasound work?Ultrasound works by bouncing sound waves off the developing fetus. Echoes from the waves are analyzed by computer to produce a moving or still picture, called a sonogram, on a screen. The technique is also called sonography.How is ultrasound performed?Two common forms of ultrasound used in pregnancy are:Transabdominal TransvaginalIn a transabdominal ultrasound exam, the health care provider or medical technician moves a handheld device, called a transducer, along the pregnant woman's abdomen. The transducer sends sound waves into the woman's uterus and also detects the echoes from those waves, which it then converts into electrical signals. The computer then assembles these signals into a picture. To get a clearer picture, the provider or technician covers the woman's abdomen with a thin layer of gel, which helps improve the transmission of sound waves. The woman also may be asked to have a full bladder during the test. The exam is painless, but many women find having a full bladder uncomfortable. In transvaginal ultrasound, the provider or technician inserts a probe into the vagina. During the test, the woman lies on her back with her feet in stirrups. This form of ultrasound may be recommended if ultrasound is needed very early in pregnancy because in early pregnancy, the uterus, ovaries and fallopian tubes are closer to the vagina than to the surface of the abdomen. In some cases, the provider may place the probe at the opening of the vagina, called translabial ultrasound. Both of these techniques can be used throughout pregnancy to allow a closer look at the cervix and lower uterus. What does an ultrasound examination include?A standard ultrasound (sometimes called a basic or level I) exam in the first trimester may take 15 to 20 minutes. This exam checks:The number and location of the gestational sacs that contain the embryo The size and age of the embryo(s) Embryonic heart activity The condition of the uterus, fallopian tubes and ovariesA standard ultrasound exam in the second or third trimesters checks:Age and size of the fetus The number of fetuses Location of the placenta Fetal heartbeat Amount of amniotic fluid Basic fetal anatomy, including the brain, spine, stomach, kidneys, bladder and all four chambers of the heartIf the provider suspects any birth defects, he or she will refer a woman for a more detailed exam called a targeted or comprehensive (sometimes called level II) exam, which may use more sophisticated ultrasound equipment. This exam can take anywhere from 30 minutes to several hours. Do all pregnant women have an ultrasound examination?Today, about 65 percent of pregnant women have an ultrasound examination (1). Many health care providers routinely offer low-risk women one ultrasound exam between 16 and 20 weeks of pregnancy. However, it is uncertain whether low-risk pregnant women benefit from routine ultrasound exams. A major study reported in 1993 found no significant difference between two groups of low-risk women (those who had two routine ultrasound exams and those who had an ultrasound only because there was some medical reason for it) in terms of the rate of preterm delivery, infant birthweight, serious complications in the newborn period or infant death (2). Some providers recommend a routine ultrasound examination at 16-20 weeks of gestation for all pregnant women performed by a skilled provider to look for fetal birth defects (3). A recent Institute of Medicine report encourages wider use of ultrasound before 20 weeks of pregnancy to more accurately establish gestational age, as a step toward learning more about the causes of preterm birth (before 37 completed weeks of pregnancy) (4). What are the medical reasons for an ultrasound exam during pregnancy?Ultrasounds are performed to identify specific conditions, such as:Suspected ectopic pregnancy: Ultrasound may be used to diagnose a pregnancy that is located in a fallopian tube or the abdomen instead of in the uterus. Possible miscarriage: If there is bleeding in early pregnancy, or if the fetal heartbeat or movement seems to have stopped, ultrasound can help determine if the fetus has died and if the woman will miscarry. Presence of more than one baby. Age of the fetus: The size of the fetus, measured using ultrasound, helps health care providers estimate the due date. This is most accurate in the first half of pregnancy. Certain birth defects: Ultrasound can be used to diagnose certain birth defects such as spina bifida. If the targeted (level II) ultrasound detects an abnormality in the development of the fetus, the health care provider may refer a woman to a medical center that specializes in more extensive ultrasound evaluation. A variety of sophisticated examinations can help determine the nature of the problem and what options may be available. Screening for Down syndrome: Recent studies suggest that a first-trimester ultrasound examination, combined with maternal blood screening, is as accurate as the traditional second-trimester blood test in screening for Down syndrome and certain other chromosomal birth defects (5, 6)). The ultrasound examination looks for a thickening of skin behind the fetal neck, called nuchal translucency, which sometimes occurs in Down syndrome. The American College of Obstetricians now recommends that all pregnant women be offered a screening test for Down syndrome (6). Fetal growth: If the uterus appears to be growing too quickly or too slowly, ultrasound can help determine whether the fetus has a growth problem or whether uterine size is related to too much or too little amniotic fluid or some other cause. Sometimes the provider recommends repeated ultrasound examinations to monitor fetal growth. Cause of second- or third-trimester bleeding: Such bleeding often is caused by placental problems, which may require special care and cesarean delivery. Fetal well-being late in pregnancy: Ultrasound and other tests (such as fetal heart rate monitoring) are used to monitor the health of the fetus during the last trimester of pregnancy (or sometimes sooner) in high-risk pregnancies. One or more ultrasounds may be recommended if the mother has a chronic health condition such as diabetes or high blood pressure or if the baby appears to be growing too slowly. In some cases, the baby may benefit from early delivery. Guiding other tests: Providers use ultrasound to guide them in performing certain diagnostic tests, including amniocentesis and chorionic villus sampling (CVS). Determining fetal position around time of delivery: A cesarean delivery may be needed if the baby is in an abnormal position.Are there other types of ultrasound?A form of ultrasound called Doppler can be used in late pregnancy to monitor fetal well-being in high-risk pregnancies. In this test, the provider uses a handheld transducer to measure the blood flow in the umbilical cord and certain fetal blood vessels. This test helps providers determine whether the fetus is getting enough oxygen.Some medical centers also use Doppler ultrasound to monitor mothers with Rh alloimmunization (7). Rh alloimmunization is an incompatibility between the blood of the mother and fetus that can cause a dangerous form of anemia in the fetus. With early detection and treatment, sometimes including early delivery or blood transfusions before birth, most affected babies survive. New ultrasound equipment that shows a three-dimensional still view (3-D ultrasound) of the fetus is now available in some medical centers and obstetricians' offices. The 3-D ultrasound is almost as detailed as a photograph and may be used when birth defects are suspected. A moving-picture version of this technology is called 4-D ultrasound. Some providers give parents these images that were taken as part of a medically indicated ultrasound examination. However, commercial sites, often unsupervised by physicians, offer 构eepsake?fetal images to parents. ACOG, the Food and Drug Administration (FDA) and the American Institute of Ultrasound in Medicine discourage the use of these non-medical ultrasound exams because the individuals conducting them may not have adequate training and may give a woman inaccurate or even harmful information (8, 9). It also is not known whether inappropriate use of ultrasound could pose a risk to the fetus.Is ultrasound safe?Ultrasound is considered safe for mother and baby when properly used by medical professionals. Health care providers have used ultrasound for more than 30 years, and they have identified no risks. Are there any drawbacks to a routine ultrasound exam?In low-risk women, ultrasound is good at ruling out problems, but not as good at detecting them. Studies suggest that a routine ultrasound exam detects between 16 and 85 percent of all structural birth defects (1). Ultrasound appears most accurate when done by an experienced examiner at a major medical center.Besides missing some birth defects, a routine ultrasound exam occasionally can suggest that a birth defect is present when none exists. While follow-up exams often show that the baby is healthy, such false alarms can cause intense worry for parents.Can problems diagnosed by ultrasound be treated?Information obtained by ultrasound often is used to alter prenatal care to improve a woman's chances of delivering a healthy baby. For example, a life-threatening fetal heart-rhythm disturbance diagnosed by ultrasound may be treated with medication while the baby is still in the uterus. The presence of certain birth defects, abnormalities of the placenta, or breech (foot-first) position may mean that a cesarean delivery could be safer for mother and baby. For babies who are suspected of having problems caused by decreased levels of oxygen, early delivery can be lifesaving. Are there other ways to reduce the risk of birth defects?Ultrasound and other prenatal tests can let a woman know if her baby has certain birth defects or other special risks. Knowing about the problems before birth provides time to plan the baby's treatment. There are some basic things all women can do to reduce their childbearing risks and increase their chances for a healthy pregnancy and a healthy baby:Plan for pregnancy by seeing a health care provider before you conceive. Take a multivitamin containing 400 micrograms of the B vitamin folic acid daily starting before pregnancy and during early pregnancy to help prevent serious birth defects of the spinal cord and brain. Get early and regular prenatal care. Eat a variety of nutritious foods, including foods that are fortified with folic acid and foods that contain folate, the natural form of folic acid found in foods. Many grain products, including flour, rice, pasta, bread and cereals, are fortified with folic acid. Folate-rich foods include green leafy vegetables, dried beans, legumes, oranges and orange juice. Begin pregnancy at a healthy weight (not too heavy or too thin), and gain the recommended amount of weight during pregnancy (25 to 35 pounds for women who begin pregnancy at a normal weight). Don't drink alcohol during pregnancy. Don't smoke during pregnancy and avoid secondhand smoke. Don't use any drug, even over-the-counter or herbal medications, unless recommended by a health care provider who knows you are pregnant. Don't eat undercooked meat or change a cat's litter box. Both can cause a parasitic infection called toxoplasmosis that can cause birth defects in the baby.You also may wish to read March of Dimes fact sheets on:Amniocentesis ] Chorionic villus sampling Maternal blood screening Genetic counseling References1. American College of Obstetricians and Gynecologists (ACOG). Ultrasonography in Pregnancy. ACOG Practice Bulletin, number 58, December 2004.2. Ewigman, B.G., et al. Effect of Prenatal Ultrasound Screening on Perinatal Outcome. The New England Journal of Medicine, volume 329, number 12, September 16, 1993, pages 821-827.3. Levi, S. Ultrasound in Prenatal Diagnosis: Polemics Around Routine Screening for Second Trimester Fetal Malformations. Prenatal Diagnosis, volume 22, 2002, pages 285-295.4. Institute of Medicine. Preterm Birth: Causes, Consequences, and Prevention. Washington, DC, National Academies Press, July 13, 2006.5. Reddy, U.M., Mennuti, M. Incorporating First-Trimester Down Syndrome Studies into Prenatal Screening. Obstetrics and Gynecology, volume 107, number 1, January 2006, pages 167-173.6. American College of Obstetricians and Gynecologists (ACOG). Screening for Fetal Chromosomal Abnormalities. ACOG Practice Bulletin, number 77, January 2007. 7. American College of Obstetricians and Gynecologists (ACOG). Management of Alloimmunization During Pregnancy. ACOG Practice Bulletin, number 75, August 2006.8. American College of Obstetricians and Gynecologists (ACOG). Nonmedical Use of Obstetric Ultrasonography. ACOG Committee Opinion, number 297, August 2004.9. American Institute of Ultrasound Medicine. Keepsake Fetal Imaging. Updated 6/22/05.January 2007