注射模热流道的传热损失和加热计算

分析了注射模热流道系统传导、对流和辐射的热损失,介绍了减小热损失的途径,并举例说明了热流道加热功率的计算方法     

Who drives divergence? Identity signaling, outgroup dissimilarity, and the abandonment of cultural tastes.

People often diverge from members of other social groups: They select cultural tastes (e.g., possessions, attitudes, or behaviors) that distinguish them from outsiders and abandon tastes when outsiders adopt them. But while divergence is pervasive, most research on the propagation of culture is based on conformity. Consequently, it is less useful in explaining why people might abandon tastes when others adopt them. The 7 studies described in this article showed that people diverge to avoid signaling undesired identities. A field study, for example, found that undergraduates stopped wearing a particular wristband when members of the "geeky" academically focused dormitory next door started wearing them. Consistent with an identity-signaling perspective, the studies further showed that people often diverge from dissimilar outgroups to avoid the costs of misidentification. Implications for social influence, identity signaling, and the popularity and diffusion of culture are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting individual subjective responses to traffic noise.

Surveyed 1,150 Ss to relate both individual subjective responses to traffic noise (e.g., annoyance) and Ss' health to traffic noise and to other nonacoustical predictors. 16 to 25% of the variance in subjective responses was accounted for by traffic noise level. Although many of the nonacoustical predictors were related to subjective responses, canonical correlations indicated that neighborhood satisfaction, anxiety, and concern about traffic accidents were most important. Negative responses increased with anxiety and concern about accidents but decreased with satisfaction. Whereas low-anxiety Ss adapted to the noise, high-anxiety Ss did not. Ss exposed to greater noise reported poorer health (e.g., hearing loss, headaches, colds) and believed more strongly that traffic noise was harmful to their health. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Front-line police officers' practices, perceptions and attitudes about the enforcement of impaired driving laws in Canada

A survey of front line police officers' practices, perceptions and attitudes regarding detection of impaired driving, processing of driving while impaired (DWI) charges, criminal court proceedings and DWI sanctions was conducted across Canada. A sample of 1545 officers of all jurisdictions across the country, representative of different types of police services (i.e. national, provincial, municipal) and types of policing (i.e. traffic, general duty) were surveyed by mail. The results, based on a 71% response rate, indicate that: an average of 7.5 charges/year are laid by officers resulting mainly from erratic driving; videotaping and mobile breath testing could improve efficiency of DWI enforcement; it takes an average of 2 h 48 min to process each DWI charge; about 2/3 of officers say plea bargaining occurs at least sometimes; the average length of DWI trial is over 4 h; less than half of officers think Crown Attorneys are adequately prepared for DWI cases; about 3/4 of officers think the accused escapes conviction on a legal technicality at least sometimes; about 30% of officers say short-term licence suspensions and other forms of discretion are used at least sometimes; DWI places fifth in priority among 15 offences, up from eighth in a 1981 survey; DWI is a priority for most police management but human resources are not adequate; and there is greater support for administrative than for Criminal Code changes. Multiple regressions indicated that the number of DWI charges laid by officers depended mainly on the officers' personal priority regarding DWI enforcement. The results suggest that many officers want to enforce DWI laws but that the numerous procedural and legal barriers that they confront often force them to exercise discretion in the laying of DWI charges.     

3D printing metals like thermoplastics: Fused filament fabrication of metallic glasses

Whereas 3D printing of thermoplastics is highly advanced and can readily create complex geometries, 3D printing of metals is still challenging and limited. The origin of this asymmetry in technological maturity is the continuous softening of thermoplastics with temperature into a readily formable state, which is absent in conventional metals. Unlike conventional metals, bulk metallic glasses (BMGs) demonstrate a supercooled liquid region and continuous softening upon heating, analogous to thermoplastics. Here we demonstrate that, in extension of this analogy, BMGs are also amenable to extrusion-based 3D printing through fused filament fabrication (FFF). When utilizing the BMGs’ supercooled liquid behavior, 3D printing can be realized under similar conditions to those in thermoplastics. Fully dense and amorphous BMG parts are 3D printed in ambient environmental conditions resulting in high-strength metal parts. Due to the similarity between FFF of thermoplastics and BMGs, this method may leverage the technology infrastructure built by the thermoplastic FFF community to rapidly realize and proliferate accessible and practical printing of metals.     

热流道系统的设计和喷嘴的选择

介绍塑料注射模热流道系统的设计原则和过程。分析热流道喷嘴的选择的原理和方法。     

What Limits the Productivity of Acid Mine Drainage Treatment Ponds?

Abstract.  Acid mine drainage (AMD) treatment ponds are very common in the U.S. Appalachian coal region and are the main source of many headwater streams. Though the water that discharges from these ponds generally meets state and federal water quality standards, there is a distinct lack of productivity in most of these ponds. Our first objective was to compare the productivity of chemically-treated, biologically-treated, and untreated AMD ponds with uncontaminated (reference) ponds. Next, we used principal component analysis and multiple regression of 20 physicochemical characteristics of these ponds to resolve which factor(s) were responsible for inhibiting productivity. We discovered that chemically-treated AMD ponds and untreated AMD ponds exhibited significantly less gross primary productivity (GPP) than reference ponds; biologically-treated ponds (containing AMD that has passed through a wetland) did not vary significantly from reference ponds. Chemically-treated ponds also had significantly less net primary productivity (NPP) than reference ponds. Community respiration did not vary among the pond types. Our test results indicated that soluble reactive phosphate concentration explained most of the variance in both GPP and NPP. Apparently, phosphate availability, not metal toxicity, regulated phytoplankton productivity in these ponds.     

Atomic origins of the high catalytic activity of nanoporous gold

Distinct from inert bulk gold, nanoparticulate gold has been found to possess remarkable catalytic activity towards oxidation reactions. The catalytic performance of nanoparticulate gold strongly depends on size and support, and catalytic activity usually cannot be observed at characteristic sizes larger than 5 nm. Interestingly, significant catalytic activity can be retained in dealloyed nanoporous gold (NPG) even when its feature lengths are larger than 30 nm. Here we report atomic insights of the NPG catalysis, characterized by spherical-aberration-corrected transmission electron microscopy (TEM) and environmental TEM. A high density of atomic steps and kinks is observed on the curved surfaces of NPG, comparable to 3-5 nm nanoparticles, which are stabilized by hyperboloid-like gold ligaments. In situ TEM observations provide compelling evidence that the surface defects are active sites for the catalytic oxidation of CO and residual Ag stabilizes the atomic steps by suppressing {111} faceting kinetics.     

Application of a Depletion-Based Stock Reduction Analysis (DB-SRA) to lake sturgeon in Lake Erie

Lake Erie supported the greatest yield of lake sturgeon within the Laurentian Great Lakes near the end of the 19th century with >2000 metric tons caught at the peak of the fishery. The fishery collapsed by the 1920s when <1% of the previous peak catch was removed. Despite closures of the fishery, lake sturgeon remain rare in Lake Erie. We applied a depletion-based stock reduction analysis (DB-SRA) to the catch of lake sturgeon from 1879 to 1929 to gain estimates of sustainable fishery reference points and the historic carrying capacity of Lake Erie for lake sturgeon. We also simulated population growth of lake sturgeon from 1929 to the present with varying assumptions of the current carrying capacity of the lake. The estimated historic carrying capacity of lake sturgeon was 22,652 metric tons. During the height of the fishery, exploitation was as high as 37% which was more than an order of magnitude greater than that required for maximum sustainable yield. Projections of the population from 1929 to 2016 suggest sufficient time has passed since the collapse of the fishery that the population should have recovered to levels that would support a fishery at maximum sustainable yield. However, lake sturgeon remain rare in Lake Erie indicating that other factors such as habitat availability may be limiting their recovery. Our estimates of carrying capacity will be informative when setting recovery targets which consider the amount of habitat loss.     

Lessons from the scrapyard: creative uses of found materials within a workshop setting

This paper focuses on a spectrum of workshops developed by the authors, collectively referred to as Scrapyard Challenges. These workshops ask participants to create a computationally designed object within a fixed time frame using cast-off materials and junk. Depending on the focus on the workshop, participants develop musical controllers, fashion-oriented wearables, or street interventions. Though operating in diverse application domains, each workshop introduces a “third place” where creative appropriation of materials and playful experimentation is the primary reward. The end results have been remarkable, with both the novice and advanced participant producing highly creative prototypes. Each variation of the workshop and selected results are shared and detailed. Future work, as well as the implications of this approach within a singular workshop setting and a classroom is discussed. The Scrapyard Challenge workshops have been deployed in six different countries and have contributed to curriculum development for a graduate-level class which utilizes the workshop principles at the MSc. Multimedia Systems course at Trinity College Dublin.