STABILITY ANALYSIS OF DATA BUOY AT SEA

A data buoy, when moored at the sea, will be influenced by different environmental factors such as wind and wave current. For this reason, the stability of a data buoy is of great importance. This paper describes the analysis and calculation of the stability of a data buoy which has a weight suspended from its bottom under normal working conditions and the influence of the distance from the weight to the bottom of the buoy on the 'righting' ability of the buoy when it is capsized. The paper also provides the curves which show the influence of the size of the weight and the distance from the weight to the bottom of the buoy on the 'righting' ability of the buoy. All these are of great reference value for the design and use of a data buoy at sea and for the design of similar floating bodies. The results from calculations agree with those from the model experiment.

SIMULATION AND ANALYSIS OF WAVE GROUPS IN A WAVE FLUME

Using the trial-error method, for a given wave spectrum, wave trains with different wave groupness, which is defined by the groupness factor GF have been simulated in a flume. The statistic characteristics are analyzed for some of these wave trains in this paper.

SILTATION INVESTIGATION IN LIANYUN HARBOR BY USING γ-RAY DENSITY GAUGE

The principle, method and mersuring equipment in studying siltaton in the Lianyun Harbor by using the γ-ray density gauge are described in this paper. From field observation and analyses, some primary principles concerning the infill rate, the distribution of silt density with depth and the consolidation rate and change of the shear strength of the silt have been found out.

Determination of Shaft Capacity for Pile under Cyclic Axial Loading in Clay

For load-controlled and displacement-controlled test data of piles cyclically axiallly loaded in clay, the displacement conditions are suggested for determining the shaft capacity. According to the suggested displacement conditions, not only the results of shaft capacity from laboratory model piles are close to those from in-situ piles, but also the results of load-controlled tests are in satisfactory agreement with those of displacement-controlled test. Moreover, based on the test data of laboratory model piles in combination with the test data published, the paper suggests the values of the normalized shaft capacity of piles under a variety of static and cyclic loading combinations.

WAVE IMPACT THEORY AND SCALE EFFECT

In this paper the theoretical analysis and calculating method for the maximal impact caused by a jet are presented and the formulas for calculation of the maximal impact of waves acting on the slope are developed. Through the comparison between the results of model tests with a model scale of 1:10 and those of prototype tests conducted in the same way in Big Wave Flume, Hannover, West Germany, the effects of model scale on the measurement of wave impact on slopes are described. In addition, a distribution regularity of the maximal impact pressure is also given.

Wind-Wave Frequency Spectra of New Dalian Port

This paper, based on wave data measured with Type 956 Directional WAVE-TRACK Buoy System at new Dalian Port for a whole year, analyses the properties of the wave frequency spectra, and derives the formula for the frequency spectrum of wind-waves.

The Astrometric Performance Test of 80 cm Telescope at Yaoan Station and Precise CCD Positions of Apophis

The 80 cm azimuthal telescope has newly been mounted at Yaoan Station,Purple Mountain Observatory since2018.The astrometric performance of the telescope is tested in the following three aspects.(a)The geometric distortion of its CCD attached.It is stable in both a single epoch and multi epochs.Eight distortion solutions are derived over about one year.The maximum values range from 0.75 to 0.79 pixel and the median values range from 0.14 to 0.16 pixel.(b)The limit magnitude of stars.About 20.5 mag(Gaia-G)stars can be detected with Johnson-V filter exposured in 300 s.The astrometric error of about 20.5 mag stars is estimated at O".14 using the fitted sigmoidal function.(c)The astrometric accuracy and the precision of stacked fast-moving faint object.24 stacked frames of the potentially hazardous asteroid(99942)Apophis were derived on 2021 April 14 and 15(fainter than18 mag)based on the ephemeris shifts.During data reduction,the newest Gaia EDR3 Catalog and Jet Propulsion Laboratory Horizons ephemeris are referenced as theoretical positions of stars and Apophis,respectively.Our results show that the mean(O-C)s(observed minus computed)of Apophis are-O".018 and O".020 in R.A.and decl.,and the dispersions are estimated at O".094 and O".085,respectively,which show the consistency of the stacked results by Astrometrica.

6T SRAM cell analysis for DRV and read stability

The present paper analyzes the hold and read stability with temperature and aspect ratio variations. To reduce the power dissipation, one of the effective techniques is the supply voltage reduction. At this reduced supply voltage the data must be stable. So, the minimum voltage should be discovered which can also retain the data. This voltage is the data retention voltage（DRV）. The DRV for 6T SRAM cell is estimated and analyzed in this paper.The sensitivity analysis is performed for the DRV variation with the variation in the temperature and aspect ratio of the pull up and pull down transistors. Cadence Virtuoso is used for DRV analysis using 45 nm GPDK technology files. After this, the read stability analysis of 6T SRAM cell in terms of SRRV（supply read retention voltage） and WRRV（wordline read retention voltage） is carried out. Read stability in terms of RSNM can be discovered by accessing the internal storage nodes. But in the case of dense SRAM arrays instead of using internal storage nodes,the stability can be discovered by using direct bit line measurements with the help of SRRV and WRRV. SRRV is used to find the minimum supply voltage for which data can be retained during a read operation. Similarly, WRRV is used to find the boosted value of wordline voltage, for which data can be retained during read operation. The SRRV and WRRV values are then analyzed for different Cell Ratios. The results of SRRV and WRRV are then compared with the reported data for the validation of the accuracy of the results.