共查询到20条相似文献，搜索用时 15 毫秒
1.
An approach was presented to intensify the mixing process. Firstly, a novel concept, the dissipation of mass transfer ability(DMA) associated with convective mass transfer, was defined via an analogy to the heat-work conversion. Accordingly, the focus on mass transfer enhancement can be shifted to seek the extremum of the DMA of the system. To this end, an optimization principle was proposed. A mathematical model was then developed to formulate the optimization into a variational problem. Subsequently, the intensification of the mixing process for a gas mixture in a micro-tube was provided to demonstrate the proposed principle. In the demonstration example, an optimized velocity field was obtained in which the mixing ability was improved, i.e., the mixing process should be intensified by adjusting the velocity field in related equipment. Therefore, a specific procedure was provided to produce a mixer with geometric irregularities associated with an ideal velocity. 相似文献
2.
Once,a gentleman was traveling in a train.He felt (1) and got down at a station in search of water.As soon as he reached the water tap[水龙头]the train started.He ran back,but(2) the train.
He asked about the next train and knew that the next train was on the next day.So he decided to find a place to(3)the night.It was getting darker and he could not find a room.He was a little(4). 相似文献
3.
Andy Adams 《海外英语》2007,(6):24-25
Hunting, in which the young man was an apt scholar, was now the order of the day. Tiburcio was an artist in woodcraft as well as in his knowledge of the habits of animals and birds. On chilly or disagreeable days they would take out the pack of dogs and beat the thickets for the javeline. It was exciting sport to bring to bay a drove of these animals. To shoot from horseback lent a charm, yet made aim uncertain, nor was it advisable to get too close range. Many a young dog made a fatal mistake in getting too near this little animal, and the doctoring of crippled dogs became a daily duty. All surplus game was sent to the ranchito below, where it was always appreciated. 相似文献
4.
Jim was in despair.Nothing was going right for him at the hospital.He had been strongly criticized.mainly for the mistake he made when called out to assist at a birth.He suspected that he was no longer trusted at the hospital and he decided to change his iob.As a result of reading an advertisement.he was able to arrange an in- terview with a doctor who was looking for a part- ner.The doctor.whose name was Scot,lived in Thorby,a small town in the North of England. 相似文献
5.
The averaging analysis was carried out to study the motion of a quasi-axisymmetrical gyrostat under a small-magnitude self-excited control troque.The common approach to investigating the problem of rigid body rotatyion under the action of a small torque known in the body frame was described.Using this approach,the problem(Grammel‘s problem for the case of small torque) that is maintaining the angular velocity of a quasi-axisymmetrical gyrostat using a control torque quadratic in the angular velocity was solved.Maintaining the angular velocity of a quasi-axisymmetrical gryostat using a control torque quadratic in the angular velocity was solved. 相似文献
6.
《海外英语》2005,(11)
What Ticket? Which Court? J got a ticket the other day.Some of you may ask: ticket for what?Well,it was not a ticket for the ballet,or an opera,or a basketball game.It was a traffic ticket.I was driving too fast.A police officer pulled me over and gave me a traffic ticket.I was,the ticketing officer said, going 50 mph (miles per hour) in a 30 mph zone.A ticket meant big trouble.When I was handed the ticket,I wished it were a ticket to the movies. 相似文献
7.
《英语自学》1995,(5)
On day,an old man was out hunting,when he saw a big deer withbeautiful horns behind a tree.It was the biggest and finest deer he hadever seen.The hunter was at the top of a cliff,the deer was at the bottom,and there was a wall of rock behind it.The old hunter knew that,if hetried to climb down the cliff,the deer would hear and see him;and itwas not possible for him to go round to the other side of the deer,because 相似文献
8.
A There was once a farmer who lived near a road. It was not a busy road, but from time to time, cars passed the farm. Near the farm gate, there was a large hole (洞) in the road. This hole was always full of water, and the drivers of the cars could not see how deep ( 深的) the hole was. They thought it was not very deep. Then when they drove into the hole, they could not drive out be- cause it was so deep. The farmer did not spend much time working on his farm. He spent most of it watching t… 相似文献
9.
In this paper, the strain energy function proposed by Shang and Cheng was generalized by introducing a nonlinear term. Void formation and growth in the interior of a sphere composed of compressible hyper-elastic material, subjected to a prescribed uniform displacement, was examined. A parametric cavitated bifurcation solution for the radial deformed function was obtained. Stability of the solution of the cavitated bifurcation equation was discussed. With the appearance of a cavity, an interesting feature of the radial deformation near the deformed cavity wall is the transition from extension to compression. 相似文献
10.
We developed a measuring instrument that had wide range, high precision, small measuring touch force. The instrument for three-dimensional （3D） surface topography measurement was composed of a high precision displacement sensor based on the Michelson interference principle, a 3D platform based on vertical scanning, a measuring and control circuit, and an industrial control computer. It was a closed loop control system, which changed the traditional moving stylus scanning style into a moving platform scanning style. When the workpiece was measured, the lever of the displacement sensor returned to the balanced position in every sample interval according to the zero offset of the displacement sensor. The non-linear error caused by the rotation of the lever was, therefore, very small even if the measuring range was wide. The instrument can measure the roughness and the profile size of a curved surface. 相似文献
11.
黄建喜 《中学生英语读写(高考版)》2003,(9)
James Cook was born on October 27, 1728, in the small Yorkshire town of Marton. Unlike the majority of naval officers of the time he was not the son of rich or noble parents. In fact he was the son of a Scottish farm laborer and a Yorkshire girl. He was intelligent enough to impress his father's employer who paid for the young James Cook's schooling. After he finished school his parentsapprenticed(使……做学徒)him to a grocer(杂货商)in whitby, where he was notespecially happy. It was there, however, that he got a taste for life on the sea. In those days the port of Whitby was a bustling place, always busy with all kinds of 相似文献
12.
There was once a farmer.He lived nearthe road.It was not a busy road,but fromtime to time,ears passed his farm. Near the farm gate,there was a largehole in the road.This hole was always full of 相似文献
13.
《英语辅导》2003,(11)
It was a stormy night. I was alone at home, reading a book, when suddenly there was a blackout. The whole house was in darkness. I knew it was a blackout though I had never experienced one before. Muttering angrily to myself, I started feeling my way to the kitchen where the candles were kept. 相似文献
14.
When papa was growing up, at the turn of the century in a village in northern Italy, education was for the rich. Papa was the son of a dirt-poor farmer. He used to tell us that be couldn't recall a single day when he wasn't working. The concept of doing nothing was never a part of his life. In fact, he couldn't fathom it. How could one do nothing? 相似文献
15.
One morning there was such a thick fog that the drivers could hardly see the roads. Mr Brown was driving a car in the street. He was driving slowly, but still he was afraid that he might bump into a tree or something. Just then he saw a red car in front and decided to follow it. 相似文献
16.
I was really happy as I set my foot in Xiangshan Park.Birds were twittering and the sunwas shining bright on the trees.I t was difficult to find such a fine day in winter.As a student who was afflicted by a large amount ofhomework,I was tired of living in the city. 相似文献
17.
郑馨媛 《英语大王(小学)》2014,(7):70-70
Last summer, my family and I went to Qingdao. Qingdao is a beautiful city. It is in the east of China. The sun was bright, the sky was blue, the sea was big and the water was dean. We swam in the sea and saw a lot of fish. Weate some seafood （海鲜）.The seafood was yummy. I loved the seafood very much. We took many photos, and l bought some nice gifts （礼物） for my friends. I had a good time in Qingdao. 相似文献
18.
19.
A parallel dynamic passive valveless micropump was designed, which consists of three layers-valve, diaphragm and electromagnetic coil. The valve was wetly etched in a silicon wafer, the diaphragm was a PDMS （polydimethyl siloxane） film spun on a silicon wafer with embedded permanent magnet posts, and the coil was electroplated on a silicon substrate. Under the actuation of the magnetic field generated by coils, the flexible diaphragm could be displaced upwards and downwards. After analyzing magnetic and mechanical characteristic of the flexible membrane and direction-dependence of the nozzle, a micropump was designed. And the relative length （L/d） of the micropump nozzle was taken 4. A 7 × 7 array of permanent magnetic posts was embedded in the PDMS film. Two diaphragms worked in an anti-step mode, which could relieve the liquid shock and increase the discharge of the micropump. The ANSYS and Matlab were adopted to analyze the actuation effect of the coil and the flow characteristic of the micropump. Results show that when actuated under a 0.3 A, 100 Hz current, the displacement of the diaphragm is more than 30 μm, and the discharge of the micropump is about 6 μL/s. 相似文献
20.
Novel approach for determining the optimal axial preload of a simulating rotary table spindle system
This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method. 相似文献