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21.
Recent theoretical and empirical studies have shown that male dominance is often at odds with female mate preference and that indirect (genetic) benefits of mate choice may not be related to male dominance. We tested whether female preference corresponded to male dominance and whether mating with dominant males conveyed benefits to offspring fitness in a small freshwater fish, the African annual killifish Nothobranchius korthausae (Cyprinodontiformes), a species without parental care. The experimental design used controlled for the effect of male age, possibility of sperm and egg depletion, and accounted for a potential that females express their preference through maternal effects by manipulation of egg mass during ovulation. By sequentially mating females with males of known dominance, we found that female N. korthausae showed no mate preference in terms of egg numbers deposited with respect to male dominance or body size and no congruent mate preference to specific males was detected. However, males sired offspring with consistently higher hatching success and the effect was repeatable across individual females. Thus, some males provided females with indirect benefits related to additive genetic quality (“good genes”) and expressed via increased hatching rate, but this benefit was not related to male dominance status or body size.  相似文献   
22.
In this study, we investigated the feasibility of using sludge water from a ready-mixed concrete plant as mixing water in concrete containing either fly ash as an additive or a superplasticizer admixture based on sulfonated naphthalene-formaldehyde condensates (SNF). The chemical and physical properties of the sludge water and the dry sludge were investigated. Cement pastes were mixed using sludge water containing various levels of total solids content (0.5, 2.5, 5, 7.5, 10, 12.5, and 15%) in order to determine the optimum content in the sludge water. Increasing the total solids content beyond 5–6% tended to reduce the compressive strength and shorten the setting time. Concrete mixes were then prepared using sludge water containing 5–6% total solids content. The concrete samples were evaluated with regard to water required, setting time, slump, compressive strength, permeability, and resistance to acid attack. The use of sludge water in the concrete mix tended to reduce the effect of both fly ash and superplasticizer. Sludge water with a total solids content of less than 6% is suitable for use in the production of concrete with acceptable strength and durability.  相似文献   
23.
HK-Ⅰ型汽油节油净化添加剂的研制   总被引:1,自引:0,他引:1       下载免费PDF全文
HK-I型汽油节油净化添加剂的研制,是为厂提高汽油本身的燃烧性能和对油路和化油器的清洗性能,从而达到降低排气污染,提高发动机动力性和节油的目的。经台架实验和汽车实跑证明,HK-I型添加剂可使油耗下降10%以上,同时也减少了CH、CO的排放.   相似文献   
24.
针对天津机场区域考虑航班运行影响,应用广义加性模型(Generalized Additive Model,GAM)建立污染物浓度预测模型,对因子间的共线性问题和交互作用进行改进,得到最优的NOx浓度预测模型.选取天津机场区域2019年11月—2020年3月环境、气象及航班数据,建立改进的GAM.结果显示:(1)改进的GAM预测效果优,可以更加准确地预测浓度峰值及变化趋势;(2)样本量会影响模型选择的因子数量及模型性能;(3)改进模型adj-R2为0.940,实测和预测NOx浓度的相关系数为0.975,预测效果好;(4)航班活动对机场区域污染物浓度影响较大.改进的GAM考虑污染物浓度与影响因子之间的复杂非线性关系及影响因子之间交互作用对污染物浓度变化的影响,使模型精度进一步提升. GAM对污染物浓度的准确预测可为机场区域污染防治提供依据.  相似文献   
25.
The objective of the present study was to explore the relationship between the dispersibility and fire-extinguishing capability of aqueous ferrocene dispersions containing gemini surfactants belonging to the same series, namely, olfin E1020, olfin PD 201, and surfynol 465. In this study, the dispersibility and ability to suppress pool fires were characterized by turbidity and extinguishing time, respectively. Ultrasonication enabled easy preparation of the aqueous dispersions of ferrocene powder containing the gemini surfactants. Visual observations and turbidity measurements clearly demonstrated that the order of dispersibility was as follows: ferrocene dispersion containing surfynol 465 ≥ ferrocene dispersion containing olfin E1020 > ferrocene dispersion containing olfin PD201. Fire suppression experiments indicated that the ferrocene diameter, in the ferrocene diameter range of 10.4–21.5 μm, negligibly influenced the extinguishing time. Furthermore, for the same ferrocene samples as were used for the turbidity measurements, the order of extinguishing ability was as follows: ferrocene dispersion containing surfynol 465 > ferrocene dispersion containing olfin E1020 > ferrocene dispersion containing olfin PD201; thus, the extinguishing ability was identical to the dispersibility order.  相似文献   
26.
The application of state of the art manufacturing processes has always been constrained by the capabilities either from technical limitations such as limited materials and complex part geometries or production costs. As a result, hybrid manufacturing processes – where varied manufacturing operations are carried out – are emerging as a potential evolution for current manufacturing technologies. However, process planning methods capable of effectively utilising manufacturing resources for hybrid processes are currently limited. In this paper, a hybrid process, entitled iAtractive, combining additive, subtractive and inspection processes, along with part specific process planning is proposed. The iAtractive process aims to accurately manufacture complex geometries without being constrained by the capability of individual additive and subtractive processes. This process planning algorithm enables a part to be manufactured taking into consideration, process capabilities, production time and material consumption. This approach is also adapted for the remanufacture of existing parts. Four test parts have been manufactured from zero and existing parts, demonstrating the efficacy of the proposed hybrid process and the process planning algorithm.  相似文献   
27.
28.
In this paper a non-layer-based additive manufacturing (AM) process named computer numerically controlled (CNC) accumulation process is presented for applications such as plastic part repairing and modification. To facilitate the CNC accumulation process, a novel three-dimensional (3D) laser scanning system based on a micro-electro-mechanical system (MEMS) device is developed for in situ scanning of inserted components. The integration of the scanning system in the CNC accumulation process enables the building-around-inserts with little human efforts. A point processing method based on the algebraic point set surface (APSS) fitting and layered depth-normal image (LDNI) representation is developed for converting the scanning points into triangular meshes. The newly developed 3D scanning system is compact and has sufficient accuracy for the CNC accumulation process. Based on the constructed surface model, data processing operations including multi-axis tool path planning and motion control are also investigated. Multiple test cases are performed to illustrate the capability of the integrated CNC accumulation process on addressing the requirements of building-around-inserts.  相似文献   
29.
SO_2 in flue gas needs to be eliminated to alleviate air pollution. As the quality of coal decreases and environmental standard requirements become more stringent, the highefficiency desulfurization of flue gas faces more and more challenges. As an economical and environmentally friendly solution, the effect of calcium formate as an additive on desulfurization efficiency in the wet flue gas desulfurization(WFGD) process was studied for the first time. Improvement of the desulfurization efficiency was achieved with limited change in p H after calcium formate was added into the reactor, and it was found to work better than other additives tested. The positive effects were further verified in a power plant, which showed that adding calcium formate could promote the dissolution of calcium carbonate, accelerate the growth of gypsum crystals and improve the efficiency of desulfurization. Thus, calcium formate was proved to be an effective additive and can potentially be used to reduce the amount of limestone slurry required, as well as the energy consumption and operating costs in industrial desulfurization.  相似文献   
30.
Very few studies have investigated the effect of genetic diversity on the behavioral and phenotypic traits linked to the competitive ability of individuals. In this study, we reared juvenile Atlantic salmon (Salmo salar) alone or with the competitive rainbow trout (Oncorhynchus mykiss) in order to: (1) to assess correlations between heterozygosity and traits related to individual competitive ability [i.e., heterozygosity–fitness correlations (HFCs)] in Atlantic salmon, and (2) to evaluate the effect of the competitive rainbow trout on any such HFCs. We also tested whether a few loci had a disproportionately large effect (i.e., the local effect hypothesis) or, on the contrary, if all loci contributed equally (i.e., the global effect hypothesis) in explaining the observed HFCs. We found significant HFCs for phenotypic traits related to the competitive ability of juvenile Atlantic salmon, i.e., the growth rate and the distance to the feeding source. Some HFCs were nonlinear, suggesting that individuals with intermediate levels of heterozygosity were favored. In addition, we found that the competition exerted by rainbow trout only weakly modified these HFCs as the relationships were highly consistent across treatments. We demonstrated that the local-effect hypothesis best explained both linear and nonlinear HFCs. Overall, our results illustrated the importance of genetic diversity in explaining the behavioral variability observed within populations. Moreover, we provide evidence that, even if a competitive species can have strong ecological effects, the relationships between genetic diversity and fitness-related traits in juvenile Atlantic salmon were not influenced by such effects.  相似文献   
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