Design of a memory polynomial predistorter for wideband envelope tracking amplifiers

Efficiency and linearity of the microwave power amplifier are critical elements for mobile communication systems. A memory polynomial baseband predistorter based on an indirect learning architecture is presented for improving the linearity of an envelope tracing （ET） amplifier with application to a wireless transmitter. To deal with large peak-to-average ratio （PAR） problem, a clipping procedure for the input signal is employed. Then the system performance is verified by simulation results. For a single carrier wideband code division multiple access （WCDMA） signal of 16-quadrature amplitude modulation （16-QAM）, about 2% improvement of the error vector magnitude （EVM） is achieved at an average output power of 45.5 dBm and gain of 10.6 dB, with adjacent channel leakage ratio （ACLR） of -64.55 dBc at offset frequency of 5 MHz. Moreover, a three-carrier WCDMA signal and a third-generation （3G） long term evolution （LTE） signal are used as test signals to demonstrate the performance of the proposed linearization scheme under different bandwidth signals.

Trial application of the envelope method to the potential ambiguity problem

The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering data.For a specific collid-ing system,ambiguous potential families can lead to different behaviors in the nearside and farside scattering components.By contrast,the envelope method can decompose the experimental data into two components with negative and positive deflection angles,respectively.Hence,a question arises as to whether the comparison between the calculated nearside(or farside)component and the derived positive-deflection-angle(or negative-deflection-angle)component can help analyze the potential ambiguity problem.In this study,we conducted a trial application of the envelope method to the potential ambiguity problem.The envelope method was improved by including uncertainties in the experimental data.The colliding systems of 16O+28Si at 215.2 MeV and 12C+12C at 1016 MeV were considered in the analyses.For each colliding system,the angular distribution experimental data were described nearly equally well by two potential sets,one of which is“surface transpar-ent”and the other is refractive.The calculated angular distributions were decomposed into nearside and farside scattering components.Using the improved envelope method,the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components,which were then compared with the calculated nearside and farside components.The capability of the envelope method to analyze the potential ambiguities was also discussed.

An envelope-based machine learning workflow for locating earthquakes in the southern Sichuan Basin

The development of machine learning technology enables more robust real-time earthquake monitoring through automated implementations. However, the application of machine learning to earthquake location problems faces challenges in regions with limited available training data. To address the issues of sparse event distribution and inaccurate ground truth in historical seismic datasets, we expand the training dataset by using a large number of synthetic envelopes that closely resemble real data and build an earthquake location model named ENVloc. We propose an envelope-based machine learning workflow for simultaneously determining earthquake location and origin time. The method eliminates the need for phase picking and avoids the accumulation of location errors resulting from inaccurate picking results. In practical application, ENVloc is applied to several data intercepted at different starting points. We take the starting point of the time window corresponding to the highest prediction probability value as the origin time and save the predicted result as the earthquake location. We apply ENVloc to observed data acquired in the southern Sichuan Basin, China, between September 2018 and March 2019. The results show that the average difference with the catalog in latitude, longitude, depth, and origin time is 0.02°,0.02°, 2 km, and 1.25 s, respectively. These suggest that our envelope-based method provides an efficient and robust way to locate earthquakes without phase picking, and can be used in earthquake monitoring in near-real time.

A New Dynamic and Vertical Photovoltaic Integrated Building Envelope for High-Rise Glaze-Facade Buildings

Substantially glazed facades are extensively used in contemporary high-rise buildings to achieve attractive architectural aesthetics.Inherent conflicts exist among architectural aesthetics,building energy consumption,and solar energy harvesting for glazed facades.In this study,we addressed these conflicts by introducing a new dynamic and vertical photovoltaic integrated building envelope(dvPVBE)that offers extraordinary flexibility with weather-responsive slat angles and blind positions,superior architectural aesthetics,and notable energy-saving potential.Three hierarchical control strategies were proposed for different scenarios of the dvPVBE:power generation priority(PGP),natural daylight priority(NDP),and energy-saving priority(ESP).Moreover,the PGP and ESP strategies were further analyzed in the simulation of a dvPVBE.An office room integrated with a dvPVBE was modeled using EnergyPlus.The influence of the dvPVBE in improving the building energy efficiency and corresponding optimal slat angles was investigated under the PGP and ESP control strategies.The results indicate that the application of dvPVBEs in Beijing can provide up to 131%of the annual energy demand of office rooms and significantly increase the annual net energy output by at least 226%compared with static photovoltaic(PV)blinds.The concept of this novel dvPVBE offers a viable approach by which the thermal load,daylight penetration,and energy generation can be effectively regulated.

Influence of Kinematic Analysis Parameters of Drag Anchor Trajectory Prediction Using Yield Envelope Method

Drag anchor is widely applied in offshore engineering for offshore mooring systems.The prediction of the invisible trajectory during its drag-in installation is challenging for anchor design in determining the anchor final position for ensuring sufficient holding capacity.The yield envelope method based on deep anchor failure for kinematic analysis was proposed as a promising trajectory prediction method for drag anchor.However,there is a lack of analysis on the effects of the parameters applied in the kinematic analysis.The current work studies the effects of the yield envelope parameters,anchor line bearing capacity factor and the anchor/soil interface friction.It is found that the accuracy of the yield envelope parameters has large impact on the prediction results based on deep yield envelopes.Analyses of cases with smooth fluke predict deeper embedment depth than that from analyses of cases with rough fluke.The decrease of the capacity factor results in the increase of the anchor embedment depth,the anchor line load,the anchor chain angle and the stable value of the normalized horizontal load component for the same drag length,while the stable value of the normalized vertical load component decreases when the capacity factor decreases.This illustrates the importance in applying reasonable parameters and improving the method for more reliable prediction of the anchor trajectory.

Hepatitis B surface antigen-negative but hepatitis B envelope antigen-positive false occult hepatitis B virus infection:A case report

BACKGROUND Occult hepatitis B infection(OBI)is characterized by the detection of hepatitis B virus(HBV)DNA in serum(usually HBV DNA<200 IU/mL)or the liver but negativity for hepatitis B surface antigen(HBsAg).The diagnosis of OBI relies on the sensitivity of assays used in the detection of HBV DNA and HBsAg.HBsAg assays with inadequate sensitivity or inability to detect HBV S variants may lead to misdiagnosis of OBI in people with overt HBV infection.CASE SUMMARY We report a HBsAg-negative but hepatitis B envelope antigen-positive patient who had a significant HBV DNA level.The patient was initially diagnosed as having OBI.However,sequence analysis revealed a unique insertion of amino acid residues at positions 120-124 in the S protein,which affects the formation of a disulfide bond that is associated with the formation of a loop.It is well known that there is an overlap between the S protein and Pol protein.We found that this new insertion site occurred in polymerase/reverse transcriptase domain,indi-cating that this insertion might be involved in HBV pathogenicity.The patient was finally diagnosed with a false OBI.CONCLUSION An insertion of amino acid residues at positions 120-124 of the S protein affects the formation of immunodominant epitopes and results in negative HBsAg levels.

一类4维3-李代数上的O-算子及导出的3-Pre-李代数

李代数的Operad理论应用于3-李代数,可自然地构造出3-Pre-李代数,其与Pre-李代数有很多相似的性质.利用4维复3-李代数的分类以及3-李代数和O-算子的结构常数的关系,使用Maple软件求解三次非线性方程组,对一类4维复3-李代数上与伴随表示相结合的O-算子进行了刻画.此外,利用所得结果,给出了这些O-算子导出的26个3-Pre-李代数的例子.

Loss of A-type lamin expression compromises nuclear envelope integrity in breast cancer

Through advances in technology,the genetic basis of cancer has been investigated at the genomic level,and many fundamental questions have begun to be addressed.Among several key unresolved questions in cancer biology,the molecular basis for the link between nuclear deformation and malignancy has not been determined.Another hallmark of human cancer is aneuploidy;however,the causes and consequences of aneuploidy are unanswered and are hotly contested topics.We found that nuclear lamina proteins lamin A/C are absent in a significant fraction(38%) of human breast cancer tissues.Even in lamin A/C-positive breast cancer,lamin A/C expression is heterogeneous or aberrant(such as non-nuclear distribution) in the population of tumor cells,as determined by immunohistology and immunofluorescence microscopy.In most breast cancer cell lines,a significant fraction of the lamin A/C-negative population was observed.To determine the consequences of the loss of lamin A/C,we suppressed their expression by shRNA in noncancerous primary breast epithelial cells.Down-regulation of lamin A/C in breast epithelial cells led to morphological deformation,resembling that of cancer cells,as observed by immunofluorescence microscopy.The lamin A/C-suppressed breast epithelial cells developed aneuploidy as determined by both flow cytometry and fluorescence in situ hybridization.We conclude that the loss of nuclear envelope structural proteins lamin A/C in breast cancer underlies the two hallmarks of cancer aberrations in nuclear morphology and aneuploidy.

Preliminary Study to Show the Effect of Building Envelope Materials on Thermal Comfort of Buildings Located in Hot Humid Climate

The main aim of this paper is to study the effect of building envelope constructed with different materials on thermal comfort of buildings located in Jeddah, Saudi Arabia. Four different buildings constructed with brick, glass, stone, and gypsum are taken into account to study the difference in temperature of the indoor and outdoor environments. Also, this paper explores the heat conducted by walls of different materials with different thicknesses. In addition, survey is conducted among the residents of Jeddah to know their perspective about thermal comfort of buildings. From the study, it is found that building envelope constructed with glass is more effective compared to envelope constructed with other materials of with least thickness of wall. Also, it is found that the envelope constructed with brick is more effective in absorbing the heat provided the thickness of the walls remains the same.

Structure defect prediction of single crystal turbine blade by dendrite envelope tracking model

The structure defects such as stray grains during unidirectional solidification can severely reduce the performance of single crystal turbine blades. A dendrite envelope tracking model is developed for predicting the structure defects of unidirectional solidification turbine blade. The normal vector of dendrite envelope is estimated by the gradient of dendrite volume fraction, and the growth velocity of the dendrite envelope (dendrite tips) is calculated with considering the anisotropy of grain growth. The solute redistribution at dendrite envelope is calculated by introducing an effective solute partition coefficient. Simulation tests show that the solute-build-up due to the rejection at envelope greatly affects grain competition and consequently solidification structure. The model is applied to predict the structure defects (e.g. stray grain) of single crystal turbine blade during unidirectional solidification. The results show that the developed model is reliable and has the following abilities: reproduce the growth competition among the different-preferential-direction grains; predict the stray grain formation; simulate the structure evolution (single crystal or dendrite grains).

Domain Ⅲ of Dengue Virus Serotype 2 Envelope: Expression at High Levels in Escherichia coli and Competitive Inhibition of Virus Entry

Obejective The domainⅢof dengue virus type 2 envelope was cloned and expressed in Escherichia coli and the inhibited effects of recombinant protein on virus was detected. Methods In this study, the domainⅢ(DⅢ) protein of the dengue virus type-2 (DENV-2) envelope (E) antigen was expressed in Escherichia coli by fusion with a carrier protein. The protein was puriifed using enzymatic cleavage and afifnity puriifcation. Rabbit immunization and antibody detection was carried out. Inhibition of DENV-2 infection was observed by DENV-2 EDⅢprotein and its immunity rabbits serum. Results The recombinant expression DENV-2 EDⅢ protein plasmid was constructed successfully. After isopropyl thiogalactoside induction, a speciifc soluble 29 kD protein was obtained, and the expression product accounted for 68.87%of the total protein of the cell lysate. Western blot demonstrated the reactivity of the recombinant protein with his-tag and DENV (Ⅰ-Ⅳ) monoclonal antibodies. The protein was puriifed using enzymatic cleavage and affinity purification. The purified recombinant EDⅢ protein inhibited the entry of DENV-2 into BHK-21 cells. DENV-2 plaque neutralization assays were carried out using serially diluted antibodies against EDⅢprotein. At a 1︰16 dilution, the antibodies produced at least 90%neutralization of the DENV-2 virus. Furthermore, the antibodies continued to exhibit high neutralization effects (approximately 80%) until the anti-EDⅢantibody titer reached 1︰1 024. Conclusions DENV-2 EDⅢwas cloned and expressed successfully. DENV-2 EDⅢprotein could be useful in the development of inexpensive dengue vaccine. The data also suggested that DENV-2 employed an attachment molecule or receptor for its entry into C6/36 mosquito cells.

Derivative Derivative-Based Envelope Design Technique for Wideband Envelope Tracking Power Amplifier with Digital Predistortion

A novel envelope design for an envelope tracking(ET)power amplifier(PA)based on its derivatives is proposed,which can trade well off between bandwidth reduc-tion and tracking accuracy.This paper theoretically analyzes how to choose an envelope design that can track the original envelope closely and reduce its bandwidth,and then demonstrates an example to validate this idea.The generalized memory polynomial(GMP)model is applied to compensate for the nonlinearity of ET PA with the proposed envelope design.Experiments are carried out on an ET system that is operated with the center fre-quency of 3.5 GHz and excited by a 20 MHz LTE signal,which show that the proposed en-velope design can make a good trade-off between envelope bandwidth and efficiency,and satisfactory linearization performance can be realized.

The Nigerian Press, Brown Envelope Syndrome （BES） and Media Professionalism： The Missing Link

Brown envelop syndrome （BES） has remained a controversial issue in any debate centred on the Nigerian press, media professionalism and media ethics. It is one of the major setbacks of media growth in Nigeria. BES is a system whereby journalists collect money or other material gifts from news sources, company executives or event organizers to cover such events and probably give it the wildest publicity as the case may be. It symbolizes the rot that has plagued the Nigerian media industry since the early 1980s to date. This paper therefore builds from an empirical study by the same authors, as well as literature materials to argue that media professionalism and the enforcement of the various ethical codes that preach professionalism are the practical ways to ensure ethical conduct and behaviour amongst journalists and other categories of media practitioners, especially in Nigeria where these are missing. This, according to the paper, is the missing link in the quest to rid the media industry in Nigeria from the monster called BES.

Comparative Studies on the Fine Structure and Elemental Composition of Envelopes of Trachelomonas and Strombomonas (Euglenophyta)

Fine structure and elemental composition of envelopes of 10 taxa of Trachelomonas and Strombomonas from natural freshwater bodies in China were studied and phylogeny of both genera were discussed. The results indicate that iron (Fe) and silicon (Si) are the primary mineral elements of the envelopes. Composition of mineral elements was uncorrelated with envelope color, however, it was highly correlated with the microarchitecture of the envelopes. Content of Si was higher than that of Fe in all species of Strombomonas and some species of Trachelomonas with rough surface. In most species of Trachelomonas, especially those with dense and smoothy surface, content of Fe was higher than that of Si. Based on the above results, we propose to assign those species of Strombomonas into Trachelomonas and consider them as a group of the latter. These species were the most primitive among the group with envelopes in Euglenaceae.

Elastic envelope inversion using multicomponent seismic data with filtered-out low frequencies

The absence of low-frequency information in seismic data is one of the most difficult problems in elastic full waveform inversion. Without low-frequency data, it is difficult to recover the long-wavelength components of subsurface models and the inversion converges to local minima. To solve this problem, the elastic envelope inversion method is introduced. Based on the elastic envelope operator that is capable of retrieving low- frequency signals hidden in multicomponent data, the proposed method uses the envelope of multicomponent seismic signals to construct a misfit function and then recover the long- wavelength components of the subsurface model. Numerical tests verify that the elastic envelope method reduces the inversion nonlinearity and provides better starting models for the subsequent conventional elastic full waveform inversion and elastic depth migration, even when low frequencies are missing in multicomponent data and the starting model is far from the true model. Numerical tests also suggest that the proposed method is more effective in reconstructing the long-wavelength components of the S-wave velocity model. The inversion of synthetic data based on the Marmousi-2 model shows that the resolution of conventional elastic full waveform inversion improves after using the starting model obtained using the elastic envelope method. Finally, the limitations of the elastic envelope inversion method are discussed.

Injective Envelopes of a Hilbert C~*Module

As in homology, the notion of injectivity is introduced in the category whose objects are Hilbert C * module over a C * algebra and whose morphism are bounded module operators. The definition of injective envelopes of an extension of a Hilbert C * modules over a C * algebra is introduced, and is characterized in terms of the injectivity and essence. It is shown that every Hilbert C * module has a unique (up to H isometrics) injective envelope if it exists. It is also shown that an extension of a Hilbert C * module is an injective envelope if and only if it is an injective and essential extension. Moreover, every Hilbert C * module over a W * algebra has a unique (up to H isometrics) injective envelope and the injective envelope of a Hilbert C * module H is maximal essential extension of H .

INVESTIGATION OF AIR FLOW ON FLIGHT DECK AND SHIPBOARD OPERATION ENVELOPE

The Shipboard Operation Envelope(SOE) is the safe boundary of the helicopter/ship dynamic interface. The night deck on a ship is usually behind the hangar, where the airflow is turbulent due to the influence of the upper structure, wind and ship speed. The turbulent airnow is the major adverse factor for the safety of shipboard operations. In this paper, the night deck abbot is analysed as the superposition of two penyndicular 2-D airflows.N-S equations are used to calculate the velocity field and the range of turbulent airflow using finite element method. The result is correspondent well with test. Incorporating the influence of the airflow and giving some restrictions on the movements of the ship and on the control margin of the helicopter, the operation envelopes are calculated. The operation envelopes include three types for hovering over the deck, taking-off from and landing on ship, and landing with a landing-aid system. These results are helpful to the pilot training and night safety.

Rolling Bearing Feature Frequency Extraction using Extreme Average Envelope Decomposition

The vibration signal contains a wealth of sensitive information which reflects the running status of the equipment. It is one of the most important steps for precise diagnosis to decompose the signal and extracts the effective information properly. The traditional classical adaptive signal decomposition method, such as EMD, exists the problems of mode mixing, low decomposition accuracy etc. Aiming at those problems, EAED（extreme average envelope decomposition） method is presented based on EMD. EAED method has three advantages. Firstly, it is completed through midpoint envelopment method rather than using maximum and minimum envelopment respectively as used in EMD. Therefore, the average variability of the signal can be described accurately. Secondly, in order to reduce the envelope errors during the signal decomposition, replacing two envelopes with one envelope strategy is presented. Thirdly, the similar triangle principle is utilized to calculate the time of extreme average points accurately. Thus, the influence of sampling frequency on the calculation results can be significantly reduced. Experimental results show that EAED could separate out single frequency components from a complex signal gradually. EAED could not only isolate three kinds of typical bearing fault characteristic of vibration frequency components but also has fewer decomposition layers. EAED replaces quadratic enveloping to an envelope which ensuring to isolate the fault characteristic frequency under the condition of less decomposition layers. Therefore, the precision of signal decomposition is improved.

血清preS1水平与慢性乙型肝炎患者肝纤维化的关系及对癌变的诊断价值

目的分析血清乙型肝炎病毒(hepatitis B virus,HBV)前S1蛋白(precursor S1 protein,preS1)与慢性乙型肝炎(chronic hepatitis B,CHB)肝纤维化及癌变进展的相关性。方法对2019年10月—2021年10月期间在青海红十字医院接受检查的228例乙肝表面抗原(hepatitis B surface antigen,HBsAg)阳性慢性HBV感染者进行回顾性分析,其中CHB患者75例、肝硬化(liver cirrhosis,LC)患者93例(LC组)、肝细胞癌(hepatocellular carcinoma,HCC)患者60例(HCC组)。根据LC和HCC组肝组织活检分析肝脏炎症活动及肝纤维化程度。结果HCC组血清preS1水平[496.32(457.63,988.0)ng/mL]和LC组[338.72(247.93,554.61)ng/mL]血清preS1水平均显著高于CHB组[113.69(87.09,177.40)ng/mL],且差异具有统计学意义(P均<0.05)。HCC组血清preS1水平亦高于LC组(P=0.002)。经受试者工作特征曲线分析,血清preS1水平鉴别诊断CHB与LC的曲线下面积(area under the curve,AUC)是0.881(95%CI:0.830~0.932),鉴别诊断CHB/LC与HCC的AUC是0.861(95%CI:0.815~0.908)。3组患者的血清preS1水平与HBsAg(rs=0.799,P<0.001)呈强正相关和Log HBV DNA(rs=0.262,P<0.001)呈弱正相关。此外LC组和HCC组血清preS1水平与肝脏炎症活动分级(rs=0.201,P=0.009)及肝纤维化分期也呈弱正相关性(rs=0.295,P<0.001)。结论血清preS1水平与血清HBsAg、HBV DNA水平和肝脏炎症和纤维化进展呈正相关,有可能成为鉴别诊断HBV相关慢性肝病肝硬化或癌变的候选标志物。