士兵的呐喊：树立真实性的尊严——解读迈克尔·黑尔的越战小说《快件》

迈克尔·黑尔的长篇小说《快件》是一部杰出的越战文学作品。该作品通过将"虚假"和"真实"进行强烈比照,书写了一个全面真实的越南战争,特别是参战美国士兵言行和思想的真实性。这些真实性向读者表明,一场不道德、非正义的战争对美国士兵和越南人民带来巨大的灾难。该主题思想主要通过电影镜头式的写作技巧以及摇滚乐式语言和意象等写作技巧表征出来,从而帮助读者从一个全新视角解读越南战争的真实图景。

Rapid Manufacturing of Metal Parts

As a key technology of rapid prototyping and manufacturing (RP&M), rapid manufacturing of metal parts is a target of RP&M. Introducing selective laser sintering (SLS), an important branch of RP&M, this paper gives a new method oriented on low power SLS system to fabricate metal parts. With this kind of technology, the mixture of metal and polymer powder is sintered first to get green part, then, after debinding and metal infiltration, dense parts are gotten. In the end, influencing factors of this technology are analyzed. At the same time, some applications are given.

SCDI Flash Memory Device Ⅱ:Experiments and Characteristics

Step channel direct injection(SCDI) flash memory device is successfully achieved by 1 2μm CMOS technology,moreover good performance is obtained.At the bias condition of V g=6V, V d=5V,the programming speed of SCDI device is 42μs.Under the condition of V g=-8V, V s=8V,the erasing speed is 24ms.Compared with the same size of conventional flash memory device whose corresponding parameters are 500μs and 24ms,respectively,the performance of SCDI device is remarkably improved.During manufacturing of SCDI device,the key technologies are to make the shallow step with appropriate depth and angle,along with eliminating the etch damage during the process of Si 3N 4 spacer.

Near-duplicate document detection with improved similarity measurement

To quickly find documents with high similarity in existing documentation sets, fingerprint group merging retrieval algorithm is proposed to address both sides of the problem:a given similarity threshold could not be too low and fewer fingerprints could lead to low accuracy. It can be proved that the efficiency of similarity retrieval is improved by fingerprint group merging retrieval algorithm with lower similarity threshold. Experiments with the lower similarity threshold r=0.7 and high fingerprint bits k=400 demonstrate that the CPU time-consuming cost decreases from 1 921 s to 273 s. Theoretical analysis and experimental results verify the effectiveness of this method.

Plant Growth Regulators, Light and Temperature Influenced Micropropagation and Successful Field Establishment of Vernonia amygdalina Del.

Vernonia amygdalina Del. is a tropical species susceptible to frost which is an annual phenomenon of the winter season of the Eastern Cape. Limited populations of the species arc in the province dieback during the winter period, thereby making large scale cultivation through conventional vegetative propagation impossible. In our effort to increasing the population of the species within the province, a micropropagation approach through tissue culture teehnology was employed. Two growth regulators （BAP ＆ NAA） were tested at four levels of concentration under continuous light and dark conditions. Plantlets were subsequently transferred to the field after acclimatization at different temperature conditions. The result of the study showed that BAP generally performs better than NAA for callus induction under continuous darkness, while direct micropropagation of shoot under continuous light condition at I mg L^-1BAP showed the best result. To achieve greater success for the rapid multiplication of the species, this study further demonstrates that the optimum temperature range for acclimatizing the species prior to the transfer of the plantlet to the field is between 23 ±3 ℃.

Rapid excavation with a newly developed retaining system: Spiral assembly steel structure

The spiral assembly steel structure, a newly developed retaining wall for the rapid excavation of small-sized foundation pits in unsaturated soil, is presented. This new type of retaining structure is prefabricated in the factory and is assembled on site in the excavation of a pit. This retaining structure is composed of several prefabricated steel structural units, in which the adjacent steel structural units are joined with connectors. Each steel structural unit has one steel pipe in the radial direction and is welded to a single piece of steel plate. After full installation in situ, the retaining structure becomes a cylindrical steel structure. With the protection afforded by this new type of retaining structure, excavation work can be completed within 24 h to a depth up to 5 m. In order to verify the reliability and effectiveness of this new retaining structure, field construction tests were conducted in Beijing, China. The test construction was monitored. The monitoring program included measuring stress in the structure, lateral earth pressure, and lateral deformation of the surrounding soil. The monitoring data from the field test were compared with the theoretical results. The results show that the proposed new structure is reliable and effective.

A Composite Model Predictive Control Strategy for Furnaces

Tube furnaces are essential and primary energy intensive facilities in petrochemical plants. Operational optimization of furnaces could not only help to improve product quality but also benefit to reduce energy consumption and exhaust emission. Inspired by this idea, this paper presents a composite model predictive control(CMPC)strategy, which, taking advantage of distributed model predictive control architectures, combines tracking nonlinear model predictive control and economic nonlinear model predictive control metrics to keep process running smoothly and optimize operational conditions. The controllers connected with two kinds of communication networks are easy to organize and maintain, and stable to process interferences. A fast solution algorithm combining interior point solvers and Newton's method is accommodated to the CMPC realization, with reasonable CPU computing time and suitable online applications. Simulation for industrial case demonstrates that the proposed approach can ensure stable operations of furnaces, improve heat efficiency, and reduce the emission effectively.

Stormwater Surface Solution in the Urban Planning

The traditional methods of storm sewers design must be supplemented by a precise and systematic analysis of the consequences of urbanization. This will ensure the reduction of the negative effects of urbanization in the process of stormwater sewer system normal functioning. As the urbanization of rural areas has been in constant progress, there was a need for the development of infrastructure system of urban planning documents that accompany urbanization. Surface storage appears to be one of the solutions that can have positive effects on the consequences of rapid urbanization in terms of preserving water quality of recipients, as well as opportunities to reduce the diameter of drain pipes downstream of surface storage. The necessary investments do not exceed the values of conventional technologies and procedures that are used for this purpose. The restriction of application of these methods is reflected in the limited space, especially in the smaller urban areas, where urbanization was a sudden and uncontrolled process. Future planning documents must contain alternatives like these, while the reservation of required space must be included in the planning documents in which the treatment of further development of the city will be found.

Characteristics of the convective bursts and their relationship with the rapid intensification of Super Typhoon Maria(2018)

For Super Typhoon Maria(2018),the multi-intensity change stages are identified and reproduced by numerical simulation.It is rather difficult to perform a perfect simulation for such a repeatedly reinforced typhoon during its long life-cycle and remote path.In this study,the rapid intensification(RI)episode is focused on to investigate the convective burst(CB)characteristics and the relationship between the CBs and the RI of Maria.For Typhoon Maria,1)the spatial pattern of the inner-core CBs in distinct shear-relative quadrants,instead of the overall inner-core CBs frequently used in previous studies,presents cyclonic rotation from downshear to upshear quadrants during RI,producing a higher efficiency for tropical cyclone(TC)spinup,which accelerates the RI process.2)Dual meanings/relationships exist between CBs and RI for Maria,in contrast to the previous argument that CBs might be an indicator or a precursor to RI.The sudden growth of CBs prior to RI provides a precursor for the upcoming RI.Additionally,the appearance of the CB peak soon after RI indicates RI could lead to more intensive deep convections.The overlap of CBs with high inertial stability inside the radius of maximum wind plays a significant role in the RI of TCs.3)The synoptic attributions to CBs are also explored for the entire troposphere,fitting in the bottom-up thinking of convection growth.The CBs might be associated with high convective available potential energy in the boundary layer,a strengthening of the deep-layer secondary circulation,and an enhanced upper-level eddy momentum flux convergence.

A method of dealing polygon’s self-intersection contour in SLA

The contour of the slices of SLA parts is composed of a great deal of small lines. When offsetting the contour to compensate for the radius of laser spot, many self-intersection contours come into being, which decrease the precision of formed parts. A new lemma to judge the local self-intersection contour and the global self-intersection contour separately is put forward, according to which self-intersection contour can be removed reliably. Meanwhile, a new beam offsetting algorithm for SLA parts is described, which brings about good resuits in the practical manufacturing process.

Investigation of Nitration Processes of iso-Octanol with Mixed Acid in a Microreactor

In this paper, the nitration characteristic of alcohols with mixed acid for the synthesis of energetic mate-rials in a stainless steel microreactor was investigated experimentally. The nitration of iso-octanol with HNO3-H2SO4 mixed acid was chosen as a typical model reaction which involved fast and strong exothermic liquid-liquid heterogeneous reaction process. The influences of mixed acid composition, flow rate, organic/aqueous flow ratio and reaction temperature have been investigated. The results indicated that the reaction could be con-ducted safely and stably in the microreactor at 25-40°C, which are enhanced compared to 15°C or below for safe operating conditions in the conventional reactors. Moreover, the 98.2% conversion of iso-octanol could be obtained and no by-products were detected in all cases.

Challenges of Implementing Participatory Irrigation Management for Food Security in Semi-arid Areas of Tanzania

Participatory irrigation management （PIM） is theoretically assumed to reduce poverty significantly, but its practical experience and challenges are yet researched and documented in Tanzania. The study aimed at assessing challenges observed during implementation of PIM approach for food security in semi-arid areas of Tanzania. Data were collected through questionnaire, participatory rapid appraisal （PRA） tools, key informants interview, Focus Group Discussion （FGD）, observation and literature review. Data collected from questionnaire were analyzed using SPSS. Data fi＇om other methods were analyzed using content analysis. The study revealed that PIM approach has contribution in improving food security at household level due to involvement of communities in water management activities and decision making, which enhanced availability of irrigation water and increased crop production. However, there were challenges observed during implementation of the approach, including the minimum participation of beneficiaries in decision making during planning and designing stages, which means that inadequate devolution of power among scheme owners, inadequate and lack of transparency on income expenditure in water utilization associations （WUAs）, water conflict among WUAs members, conflict between farmers and livestock keepers and conflict between WUAs and village government leaders regarding training opportunities and status. The rules and regulation of WUAs were not legally recognized by the national courts and few farmers who planted trees around water sources. However, it was realized that some of the mentioned challenges were rectified by farmers themselves and facilitated by government officials. The study recommends that the identified challenges need to be rectified for farmers to realize more on the importance of PIM approach as it was realized in other Asian countries.

Behavioral assessments of the aversive quality of pain in animals

Animals and humans share similar mechanisms of pain detection and similar brain areas involved in pain processing.Also,they show similar pain behaviors,such as reflexed sensation to nociceptive stimuli.Pain is often described in sensory discrimination （algosity） and affective motivation （unpleasantness） dimensions.Both basic and clinical findings indicate that individuals with chronic pain usually suffer more from pain-associated affective disturbances than from the actual pain sensations per se.Although the neural systems responsible for the sensory component of pain have been studied extensively,the neural mechanisms underlying negative affective component are not well understood.This is partly due to the relative paucity of animal paradigms for reliable examination of each component of pain.In humans,the experience of pain and suffering can be reported by language,while in animals,pain can only be inferred through physical and behavioral reactions.Animal behaviors,cognitive psychology and functional brain imaging have made it possible to assess pain affection and pain memory in animals.Animals subjected to either neuropathic injury or inflammatory insult display significant conditioned place aversion to a pain-paired environment in behaviors.The present review aims to summarize the common methods of affective unpleasantness assessment in rats.

Semi-liquid metal and adhesion-selection enabled rolling and transfer(SMART) printing:A general method towards fast fabrication of flexible electronics

Recent breakthrough in eutectic gallium-indium alloy has revealed its great potential in modern electronic engineering. Here, we established a general method towards super-fast fabrication of flexible electronics via semi-liquid metal and adhesion-selection enabled rolling and transfer (SMART) printing on various substrates. Based on the semiliquid metal and its adhesion-difference on specifically designed target materials, we demonstrated that the rolling and transfer printing method could serve to rapidly manufacture a wide variety of complicated patterns with high resolution and large size. The process is much faster than most of the currently existing electronic fabrication strategies including liquid metal printing ever developed, and the cost either in time or consumption rate is rather low. As illustrated, a series of functional flexible and stretchable electronics such as multiple layer and large area circuits were fabricated to show their superior merit in combination with electrical conductivity and deformability. In addition, it was also demonstrated that the electronics fabricated in this way exhibited good repeatablity. A most noteworthy advantage is that all the fabrication processes could be highly automatic in the sense that user-friendly machines can thus be developed. This method paves a practical way for super-fast soft electronics manufacture and is expected to play an important role in the coming industry and consumer electronics.

Precise simulation of surface acoustic wave devices using frequency-dependent coupling-of-modes parameters

Herein we extract all the frequency-dependent coupling-of-modes （COM） parameters, which will be used to the rapid simulation and optimal design of surface acoustic wave （SAW） devices. FEM/BEM is used to calculate the exact field distributions of forward and backward surface acoustic waves within a finite-length periodic grating at every frequency. The middle compo- nent of the grating, regarded as a periodic structure, is selected to be investigated which can satisfy the presupposition of the COM model. From these field distributions, the values of P-matrix elements of one cell are calculated. The COM parameters taken as functions of frequency are accurately obtained. Specifically, the frequency-dependent relationships of reflection coefficient and propagation velocity are obtained independently. Using the resultant COM parameters, a one-port resonator on the substrate of 128°YX-LiNbO3 is simulated and the admittance curve shows good agreement with the simulating results using FEM/BEM. These results verify the validity and accuracy of this method.

Stretchable SnO2-CdS interlaced-nanowire film ultraviolet photodetectors

Stretchable ultraviolet photodetectors with fast response have wide applications in wearable electronics and implantable biomedical devices. However, most of the conventional binary oxide nanowires based photodetectors exhibit slow response due to the presence of a large number of surface defects related to trapping centers. Herein, with interlaced SnO2-CdS nanowire films as the sensing materials, we fabricated stretchable ultraviolet photodetectors with significantly improved response speed via a multiple lithographic filtration method. Systematic investigations reveal that the interlaced-nanowire based photodetectors have lower dark current and much higher response speed(more than 100 times) compared with pure SnO2 nanowire based photodetectors. The relevant carrier generation and transport mechanism were also discussed. In addition, due to the formation of waved wrinkles on the surface of the nanowires/PDMS layer during the prestretching cycles, the SnO2-CdS interlaced nanowire photodetectors display excellent electrical stability and stretching cyclability within 50% strain, without obvious performance degradation even after 150 stretching cycles. As a simple and effective strategy to fabricate stretchable ultraviolet photodetectors with high response speed, the interlacednanowire structure can also be applied to other nanowire pairs, like ZnO-CdS interlaced-nanowires. Our method provides a versatile way to fabricate fast speed ultraviolet photodetectors by using interlaced metal oxide nanowires-CdS nanowires structures, which is potential in future stretchable and wearable optoelectronic devices.

A synthetic criterion for early recognition of cutting chatter

Cutting chatter is a violent self-excited vibration between a tool and a workpiece.Its negative effects mainly include poor surface quality,inferior dimensional accuracy,disproportionate tool wear or tool breakage,and excessive noise.Therefore,early recognition and online suppression of chatter vibration are necessary.This paper proposes a novel synthetic criterion(SC)for early chatter recognition.The proposed SC integrates standard deviation(STD)and one-step autocorrelation function(OSAF).Moreover,this paper revised the fast algorithm of OSAF.We can quantitatively divide a chatter vibration signal into three stages,which are stable stage,transition stage and chatter stage according to the SC.Compared with STD,the SC can improve the reliability of chatter recognition and the threshold of SC is not sensitive to variable cutting conditions.This paper presents an original algorithm of SC and its fast algorithm in detail.The fast algorithm of SC in this paper improves the computation efficiency compared with the original algorithm of SC.To validate the effectiveness of the proposed SC,a series of milling experiments were conducted under different cutting conditions.In these experiments,the vibration signals were acquired by two accelerometers mounted on the spindle house.The experimental results showed that the proposed SC could effectively recognize chatter vibration at an early stage of chatter vibration,which saved valuable time for online chatter suppression.