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991.
992.
An intensive computer keyboard training course, based on an information processing model of man, was tested on a variety of personnel in work. Over a one or two week period, 241 adult subjects were trained. Subjects achieved mean speeds of 7.1 words per minute (WPM) after the second and 13.7 WPM after the ninth lesson. Significant decreases in errors per minute (EPM) occurred from 2.67 to 1.78. Previous experience with a keyboard and being female were factors associated with enhanced keyboard operating performance. Compressing the ten lessons from two into one week reduced the effectiveness of the programme. 相似文献
993.
994.
V.D. Berkut V.V. Kovtun N.N. Kudryavtsev S.S. Novikov A.I. Sharovatov 《International Communications in Heat and Mass Transfer》1985,12(5):567-575
A technique for determining time-resolved heterogeneous recombination probabilities W is developed which is based on comparison of the measured and calculated heat fluxes to a flat wedge-like plate set at a small expansion angle to a supersonic dissociated gas flow behind a shock wave with the typical parameters: pressure of 100 mm Hg, temperature of 3000 – 4000 K, and velocity of 2.5 – 3.0 km s?1. 相似文献
995.
This reply clarifies that it is possible to change the plane of cut by filtering a tomogram, if the presence of the out-of-focus images is tolerated, because the (projected) images of all the layers are superimposed on the film and any filtering will process all these images simultaneously. 相似文献
996.
997.
Yu. M. Lakhtin G. N. Neustroev N. I. Sologubova L. P. Frolova 《Metal Science and Heat Treatment》1987,29(5):359-364
Conclusion Carbonitriding at 700°C in a mixture of 70–30% of ammonia and 30–70% of endogas (or natural gas) is recommended for the production of a diffusion layer with a good set of operational properties (for example, with high wear resistance).Moreover, the use of a gaseous atmosphere based on commercial nitrogen (50–90%) with ammonia, natural-gas, oxygen, or carbon dioxide additives is promising for carbonitriding at 700°C. Here, this medium should not contain more 0.5–1.0% of O2 and 3% of CO2. The nitrogen-based gaseous atmospheres ensure the attainment of quality diffusion layers with decreased risk of explosion and saving of energy resources.Moscow Automobile Traffic and Highway Construction Institute. Nongovernmental Production Union "All-Union Scientific-Research and Experimental Design Institute for Trade Machine Construction. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 32–36, May, 1987. 相似文献
998.
The nonlinear Boussinesq equation is used to understand water table fluctuations in various ditch drainage problems. An approximate solution of this equation with a random initial condition and deterministic boundary conditions, recharge rate and aquifer parameters has been developed to predict a transient water table in a ditch-drainage system. The effects of uncertainty in the initial condition on the water table are illustrated with the help of a synthetic example. These results would find applications in ditch-drainage design.Notation
A
/ tanh t
-
a
lower value of the random variable representing the initial water table height at the mid point
-
a+b
Upper value of the random variable representing the initial water table height at the midpoint
-
B
tanh t
-
C
4/
-
h
variable water table height
- h
mean of the variable water table height
-
h
m
variable water table height at the mid point
- h
m
mean of the variable water table height at the mid point
-
K
hydraulic conductivity
-
L
half spacing between the ditches
-
m
0
initial water table height at the mid point
-
N
Uniform rate of recharge
-
S
specific yield
-
t
time of observation
-
x
distance measured from the ditch boundary
-
(4/SL)(NK)1/2
-
(L/4)(N/K)1/2
-
dummy integral variable 相似文献
999.
J. A. Dayton V. O. Heinen N. Stankiewicz T. M. Wallett 《Journal of Infrared, Millimeter and Terahertz Waves》1987,8(10):1257-1268
NASA Lewis Research Center is engaged in a program to develop a series of backward wave oscillators (BWO's) for the frequency range 500 to 2000 GHz. Generically BWO's are electron beam traveling wave tubes operating in a dispersive regime in which the group velocity and the phase velocity of the induced electromagnetic wave are in opposite directions. The oscillation frequency of a BWO is controlled by the electron beam velocity (anode voltage). Such tubes because of their frequency tunability, phase locking capability, and large bandwidth are ideal local oscillators for heterdyne receiver/spectrometers. The design of the BWO's will be discussed with emphasis on the etched slow wave structure, zero compression electron beam, long life cathode, and moderate operating voltages. 相似文献
1000.
N N Tupitsyn E B Mechetner A Iu Baryshnikov E N Rozinova 《Eksperimental?nai?a onkologii?a》1987,9(4):30-34
Expression of erythroid antigens identifying with the use of monoclonal antibodies (mab) HAE3 and HAE9 was studied in 333 patients with different types of hemoblastoses. Frequency of erythroid variants based on the reaction with mab was 5.7%. In 2.4% of cases erythroid markers were the only indication on the nature of leukemia. In 2.7% of cases the types of leukemia were accounted for as "mixed" ones, i.e. erythrolymphoid and erythromyeloid variants. Only in 0.6% of cases erythroid variant was detected by the morphological criteria. 相似文献