Determining the time and space domains forestimating b value in seismic zoning

To take the seismic zone that includes the great shock with M S8.5 as the statistical unit of estimating b value can often lead to more large variance, because the seismogenic zone of the great shock with M S8.5 are larger than that delineated in general seismic zone. Two-level statistical units are considered in this paper. The seismic province is the first level unit that is suitable for group of earthquakes including the great shock of M S8.5. A seismic province can be divided into several seismic zones. They can be taken as the second level unit for group of quakes in which the super magnitude of the greatest shock do not exceed 8. Because of the nonstationarity in time of seismic activity, the unbalancedness of data and differential of seismic temporal series feature in different areas need to be considered when we select the time period for estimating b value. According to local conditions, the time period is selected at one′s discretion in order to reflect seismicity level of this statistical unit in future 100 years.

Predictive value of enhanced CT Hounsfield unit value for central lymph node metastasis in Hashimoto’s thyroiditis with papillary carcinoma

Objective To investigate the diagnostic and predictive value of enhanced CT Hounsfield unit value for central lymph node metastasis(CLNM)in patients with Hashimoto’s thyroiditis(HT)complicated with papillary thyroid carcinoma(PTC).Methods The CT images of HTs with PTC confirmed by operation and pathology from 88 patients were analyzed retrospectively.Among them,50 cases of CLNM were all negative and 38 cases of CLNM were all positive.One lymph node was selected as the study subject in each case.The average HU values(AHUVs)and maximum HU values(MHUVs)were measured on the enhanced CT.The diagnostic efficacy of the two parameters for diagnosing CLNM was analyzed by the receiver operating specificity curve(ROC),and the best cut-off values were obtained,which were used to predict 103 HT with PTC CLNM in the validation group.Results The AHUVs of negative group and positive group were(63.79±15.34)HU and(90.92±18.04)HU(t=8.828,P<0.001).The MHUVs of negative group and positive group were(77.08±15.30)HU and(108.79±18.37)HU,respectively(t=7.615,P<0.001).The AUCs for AHUVs and MHUVs for the diagnosis of CLNM-positive was 0.870 and 0.906,and the cut-off values were 84.0 HU and 96.5 HU,respectively.The sensitivity,specificity,and accuracy of predicting CLNM positivity in the validation group using AHUVs≥84.0 HU were 35.7%,95.1%,and 70.9%,respectively,and MHUVs≥96.5 HU were 38.1%,93.4%,and 70.9%,respectively.Conclusion AHUVs≥84.0 HU and MHUVs≥96.5 HU have high specificity for the diagnosis of HT with PTC CLNM,which can provide an important basis for clinical treatment decision.

The Meaning of an Infinitely Great Velocity

An instantaneous velocity where a moment of the clock only corresponds to an arbitrary distance or position in space cannot be implied in Axiom 1, but it indicates that there is only one dimensional existence, space or time, where a certain moment only corresponds to itself specifically, not to any other time or any given length of space. Further, a definition of velocity that consists of two dimensions representing the relationship between space and time is not valid and there is only one-dimensional space or time that is independent of each other in Axiom 1. As a result, the principle of relativity and the principle of the constant velocity of light are replaced by the principle of an inertial system and the principle of universal invariant velocity in Axiom 1. Unlike two dimensions whose magnitude is determined by the ratio, the magnitude of a single dimension is determined by the unit values of one dimension, which indicates that an infinitely great velocity is meaningless. Further, if the two inertial systems are infinite versus finite in Axiom 3, then this extension of the infinitely great velocity can be defined as inextensible.

An integrated multi-energy flow calculation method for electricity-gas-thermal integrated energy systems

The modeling and multi-energy flow calculation of an integrated energy system (IES) are the bases of its operation and planning. This paper establishes the models of various energy sub-systems and the coupling equipment for an electricity-gas-thermal IES, and an integrated multi-energy flow calculation model of the IES is constructed. A simplified calculation method for the compressor model in a natural gas network, one which is not included in a loop and works in constant compression ratio mode, is also proposed based on the concept of model reduction. In addition, a numerical conversion method for dealing with the conflict between nominal value and per unit value in the multi-energy flow calculation of IES is described. A case study is given to verify the correctness and speed of the proposed method, and the electricity-gas-thermal coupling interaction characteristics among sub-systems are studied.