Multivariate statistical analysis of a high rate biofilm process treating kraft mill bleach plant effluent.

This study reports on a multivariate analysis of the moving bed biofilm reactor (MBBR) wastewater treatment system at a Canadian pulp mill. The modelling approach involved a data overview by principal component analysis (PCA) followed by partial least squares (PLS) modelling with the objective of explaining and predicting changes in the BOD output of the reactor. Over two years of data with 87 process measurements were used to build the models. Variables were collected from the MBBR control scheme as well as upstream in the bleach plant and in digestion. To account for process dynamics, a variable lagging approach was used for variables with significant temporal correlations. It was found that wood type pulped at the mill was a significant variable governing reactor performance. Other important variables included flow parameters, faults in the temperature or pH control of the reactor, and some potential indirect indicators of biomass activity (residual nitrogen and pH out). The most predictive model was found to have an RMSEP value of 606 kgBOD/d, representing a 14.5% average error. This was a good fit, given the measurement error of the BOD test. Overall, the statistical approach was effective in describing and predicting MBBR treatment performance.     

Positive holes in magnesium oxide. Correlation between magnetic, electric, and dielectric anomalies

Magnetic susceptibility measurements of high purity MgO single crystals (<50-wt. ppm transition metals) by means of a vibrating-sample magnetometer shows an anomaly at 800 K. At the same temperature the electric conductivity increases anomalously, the static dielectric constant epsilon increases from 9 to approximately 150, a pronounced positive surface charge appears, and Fe2+ in the MgO matrix oxidizes to Fe3+. The data are consistent with O2(2-) (peroxy) defects, representing self-trapped, spin-paired positive holes at Mg2+ vacancy sites. Diamagnetic at low temperatures, the holes start to decouple their spins > 600 K, probably forming at first V0 centers (two O- at an Mg2+ vacancy), then V- centers (single O- at an Mg2+ vacancy), and releasing mobile O- states. These O- represent itinerant charge carriers on acceptor levels near the O 2p-dominated valence band and conduct by O- /O2- valency fluctuations. The O- concentration is of the order of 8 X 10(19) cm-3.     

利益相关者对辐射防护的看法

辐射照射许可标准及其制定方法必须体现维护健康和民主的原则。当辐射危害的科学是不确定的时候,举证没有构成危险的责任在于危险源的一方,而不在可能受影响的公众的或工作人员一方。科学论证的进程必须对公众透明,必须考虑所有的相关危险问题和疾病终点(不仅是癌),必须考虑受到辐射危险的人们的实际经验和意见。科学家们往往太轻视公众的经验和权益,尽管常常证明公众和工作人员的意见对于制定辐射防护原则是有价值的。既要礼貌地体现工作人员和公众的关注、观点和经验,又要维护高标准的科学工作,必须是标准制定过程的基础部分。ICRP阐明的“强加的危险必须伴有明确的利益”的原则应当是标准制定过程中一个更加明确的部分,必须保证所有已知的危险是被揭示出来了,所怀疑的危险如某些放射性核素与紊乱荷尔蒙的化学品之间可能的协同作用是得到了认真的考虑。最后,鉴于许多放射性核素的长寿命特性和未来自然的、社会的、经济的以及其它条件的巨大不确定度,在制定标准的过程中如何体现子孙后代的权益是一个困难的但是至关重要的的问题。     

Advanced unipolar electrolysis

Substantially reduced capital costs and an efficiency exceeding 85% are foreseen for advanced unipolar electrolysers. The new equipment preserves the recognized advantages of the unipolar design. Two generations of electrolyser development are discussed. The first generation is based on conservative modifications to proven commercial designs and on the use of electrode activation. The resulting concepts have been fully demonstrated, and representative data are presented. The second-generation designs incorporate modifications which allow operation at current densities of 5 kA m⁻². Results are reported which demonstrate feasibility in pilot cells. Both generations of advanced unipolar electrolysers will produce hydrogen at atmospheric pressure. Compression costs are reviewed. It is concluded that hydrogen compression external to the gas-generating equipment is preferred to electrolysis at high pressures, for reasons of safety and economy.     

Separator materials for use in alkaline water electrolysers

Separator materials suitable for use in industrial alkaline water electrolysers are surveyed, including both inorganic and organic materials. The properties which make asbestos diaphragms unsuitable for use above 100°C are also reviewed.In summary, potassium titanate and polyantimonic acid separator materials perform well in high-temperature alkali. Oxide-coated metallic diaphragms merit further attention. Polysulfone and polyphenylene sulfide polymers are promising, but will need definite improvement in their wettability. Asbestos stabilization by silicate electrolyte additions may be viable.     

Fluidized-bed electrowinning — I. General modes of operation

An analysis is presented of the changes in properties of a fluidized-bed cathode during continued electrowinning use. Control of the particle-size distribution in the bed is achieved by periodic withdrawal of powder equal in weight to the electrowon metal, plus a small fraction of original bed weight. The electrode is restored to its original weight by addition of a suitable quantity of the starting material. The analysis demonstrates that the fluidized electrode approaches a steady-state condition which depends primarily on the detailed schedule under which it is operated, with the initial bed material exerting only a minor influence. Suitable operating schedules are discussed.     

Estrous detection intensity and accuracy and optimal timing of insemination with automated activity monitors for dairy cows

The objectives of this observational study were to assess the ability of automated activity monitoring (AAM) to detect estrus for first insemination, the accuracy of detection, and the optimum interval from the estrus alert from the AAM system to insemination. Four commercial farms using 1 of 2 commercial AAM systems were studied over 1 yr. Cows were inseminated between 55 and 80 d in milk (DIM) based on AAM only, then by a combination of AAM and timed artificial insemination (AI). Blood progesterone was measured in 1,014 cows at wk 5, 7, and 9 postpartum; purulent vaginal discharge (PVD) was assessed at wk 5; and lameness and BCS at wk 7. Overall, AAM detected 83% of cows in estrus by 80 DIM. Cows that had 3 serum progesterone <1 ng/mL, had PVD, or were both lame and had BCS ≤2.5 has lesser odds of being detected in estrus by 80 DIM (62, 68, and 53%, respectively). Blood samples were collected on the day of 445 AI based on AAM and 323 timed AI. The proportion of cows not in estrus (progesterone >1 ng/mL) on the day of AI was similar between AAM (4 ± 1.8%) and timed AI (3 ± 1.2%). Managers elected, based on subjective criteria, not to inseminate 17% of cows for which an AAM estrus alert was issued, of which 43% were not in estrus. Activity data were extracted from AAM software for 1,399 AI. Onset of estrus was calculated using the same or similar data processing criteria as the AAM system. Producers recorded the time of AI. The interval from onset of estrus to AI was categorized as 0 to 8, 8 to 16, or 16 to 24 h. We found no effect of AAM system on the probability of pregnancy per AI, but noted an interaction of interval with parity. For multiparous cows, the probability of pregnancy per AI was 31%, which did not differ with the interval to AI. For primiparous cows, the odds of pregnancy were greater if AI occurred 0 to 8 h (49%) than 8 to 16 (36%) or 16 to 24 h (31%) after the estrus alert from the AAM. Automated activity monitoring can detect estrus for first AI in just over the length of 1 estrous cycle for over 80% of cows, but the remainder would likely require intervention for timely insemination. For multiparous cows, performing AI based on AAM once per day would not affect pregnancy per AI, but for primiparous cows AI within 8 h of the onset of estrus may be advantageous.     

Efficient Pattern Generation for Small-Delay Defects Using Selection of Critical Faults

Testing for small-delay defects (SDDs) has become necessary as technology further scales. Existing tools and methodologies for generating SDD patterns suffer from: limited long-paths sensitization capability, overwhelming pattern volume, time-consuming pattern generation process, and vague evaluations of pattern quality. Such situation places patterns in a dilemma where the generation and application effort are huge yet the results cannot reflect the physical phenomena clearly enough for correct binning and diagnosis. In this paper, we focus on establishing a pattern generation flow that produces patterns of high application value. Firstly, critical faults are identified in order to generate high-quality original pattern repository with n-detect ATPG.A novelpattern evaluation and selection method that further minimizes pattern count while maintaining the SDD detection ability is then presented. Top-off ATPG is then performed to ensure meeting the target fault coverage. Along with the flow, multiple evaluation metrics are also proposed to measure the pattern’s efficiency on SDD coverage, unique SDD detection, detectable SDD size, long path distribution, etc. Experimental results demonstrate that the proposed critical fault-based method improves long path sensitization efficiency by 2.5× without impairing its average delay and saves approximately 80 % CPU runtime compared with total fault-based method. Comparing with timing-aware ATPG, the generated pattern set detects equivalent or even more SDDs with significantly reduced pattern count.