连续调查的整群抽样

本文讨论了连续调查中应用普查方法时的整群抽样和分层整群抽样。     

Physics of transparent conductors

Transparent conductors (TCs) are materials, which are characterized by high transmission of light and simultaneously very high electrical DC conductivity. These materials play a crucial role, and made possible numerous applications in the fields of electro-optics, plasmonics, biosensing, medicine, and “green energy”. Modern applications, for example in the field of touchscreen and flexible displays, require that TCs are also mechanically strong and flexible. TC can be broadly classified into two categories: uniform and non-uniform TC. The uniform TC can be viewed as conventional metals (or electron plasmas) with plasma frequency located in the infrared frequency range (e.g. transparent conducting oxides), or ultra-thin metals with large plasma frequency (e.g. graphen). The physics of the nonuniform TC is much more complex, and could involve transmission enhancement due to refraction (including plasmonic), and exotic effects of electron transport, including percolation and fractal effects. This review ties the TC performance to the underlying physical phenomena. We begin with the theoretical basis for studying the various phenomena encountered in TC. Next, we consider the uniform TC, and discuss first the conventional conducting oxides (such as indium tin oxide), reviewing advantages and limitations of these classic uniform electron plasmas. Next, we discuss the potential of single- and multiple-layer graphene as uniform TC. In the part of the paper dealing with non-uniform metallic films, we begin with the review of random metallic networks. The transparency of these networks could be enhanced beyond the classical shading limit by the plasmonic refractive effects. The electrical conduction strongly depends on the network type, and we review first networks made of individual metallic nanowires, where conductivity depends on the inter-wire contact, and the percolation effects. Next, we review the uniform metallic film networks, which are free of the percolation effects and contact problems. In applications that require high-quality electric contact of a TC to an active substrate (such as LED or solar cells), the network performance can be optimized by employing a quasi-fractal structure of the network. We also consider the periodic metallic networks, where active plasmonic refraction leads to the phenomenon of the extraordinary optical transmission. We review the relevant literature on this topic, and demonstrate networks, which take advantage of this strategy (the bio-inspired leaf venation (LV) network, hybrid networks, etc.). Finally, we review “smart” TCs, with an added functionality, such as light interference, metamaterial effects, built-in semiconductors, and their junctions.     

Investigation of Homogeneity and Matter Distribution on Large Scales Using Large Quasar Groups

We use 20 large quasar group (LQG) samples in Park et al. (2015) to investigate the homogeneity of the 0.3 z 1.6 Universe (z denotes the redshift). For comparison, we also employ the 12 LQGs samples at 0.5 z 2 in Komberg et al. (1996) to do the analysis. We calculate the bias factor b and the two-point correlation function ξ_LQG for such groups for three different density profiles of the LQG dark matter halos, i.e. the isothermal profile, the Navarro-Frenk-White (NFW) profile, and the (gravitational) lensing profile. We consider the CDM (cold dark matter plus a cosmological constant ) underlying matter power spectrum with Ω_m = 0.28, Ω_Λ= 0.72, the Hubble constant H₀ = 100 h·km·s^-1·Mpc^-1 with h = 0.72. Dividing the samples into three redshift bins, we find that the LQGs with higher redshift are more biased and correlated than those with lower redshift. The homogeneity scale RH of the LQG distribution is also deduced from theory. It is defined as the comoving radius of the sphere inside which the number of LQGs N(< r) is proportional to r³ within 1%, or equivalently above which the correlation dimension of the sample D₂ is within 1% of D₂ = 3. For Park et al.'s samples and the NFW dark matter halo profile, the homogeneity scales of the LQG distribution are R_H ～ 247 h^-1·Mpc for 0.2 < z ≤ 0.6, R_H ～ 360 h^-1·Mpc for 0.6 < z ≤ 1.2, and R_H ～ 480 h^-1·Mpc for 1.2 < z 1.6. The maximum extent of the LQG samples are beyond RH in each bin, showing that the LQG samples are not homogeneously distributed on such a scale, i.e. a length range of ～ 500 h^-1·Mpc and a mass scale of ～ 10¹⁴M_⊙. The possibilities of a top-down structure formation process as was predicted by the hot/warm dark matter (WDM) scenarios and the redshift evolution of bias factor b and correlation amplitude ξ_LQG of the LQGs as a consequence of the cosmic expansion are both discussed. Different results were obtained based on the LQG sample in Komberg et al. (1996) and the possible reasons for such differences were discussed.     

Bootstrapping to choose an estimator after sampling on two occasions

Email: a.brint{at}sheffield.ac.uk Received on 22 August 2007. Accepted on 13 June 2008. When successive surveys are undertaken so as to keep a populationestimate up to date, combining the data from the most recentsurvey with data from earlier surveys is more efficient thanjust using the most recent survey. The standard approach tocombining the data forms separate estimates from the set ofitems observed on the earlier occasion and the set observedon the later occasion and then forms a combined estimate. Theapproach assumes that the population is very large and thatthe observed values of the variable of interest are continuous.In many situations, neither assumption is particularly appropriate.This paper compares an alternative approach with the standardapproach and finds that the alternative approach sometimes providesa better estimator. It then puts forward an improved estimatorbased on choosing between these approaches using a bootstrapprocedure.     

Significance of fluid regime and wetted area in biofilm reactors

Mass transfer within microbial films was described using Monod-type biological kinetics in terms of properties of filter media and feed solution. The performance characteristics of a trickling filter were thus modeled. The model enables one to consider the effect of inlet substrate concentration and flow rate upon the removal efficiency. For this purpose a second-order partial differential equation describing the dispersion phenomena inside the liquid layer was solved under special boundary conditions and used to determine substrate flux into the biofilm. A uniform biofilm thickness was considered. The model is based on computer techniques and the numerical evaluation of the normalized biofilm mathematical model. A design procedure was also given to calculate biological filters. The numerical model was also applied to experimental data to demonstrate its validity.     

Good and bad market research: A critical review of Net Promoter Score

Net Promoter Score, touted as the “single customer metric you need” and calculated from customers' answer to one simple question about their loyalty, has been in use since 2003 and adopted in a wide variety of settings. However, it has not lived up to its claimed benefits. This article evaluates the NPS approach in terms of its positive and negative results. This article is for people interested in NPS, still considering implementing NPS in their company, or interested in its technical underpinnings. It points out the benefits and shortcomings and explains why, and it describes what can be done to achieve the outcomes NPS theory claimed it would produce, but has not. The article is written in two parts for quite distinct audiences: firstly, for executives and managers who need customer data and information to make marketing decisions; and secondly, for market researchers, statisticians, and business analysts who are responsible for capturing and providing reliable, understandable, and meaningful customer data to the executives and managers who need the information. Consequently, the two sections are written in two different styles. The first section takes the form of a summary for managers and executives of our findings and recommendations in language aimed at business leaders; the second section provides a detailed analysis and critical review of NPS for market researchers, statisticians, and business analysts. Both sections present a better solution than NPS for understanding what customers value, delivering the best value to customers, winning market share, and creating truly loyal customers.     

Tagungsbericht ASTI 1969

Design and specifications of a 4-channel logging tool for simultaneous measurement of natural gamma-radiation, caliper and scattered gamma-radiation from a ¹³⁷Cs source spaced 15 and 35 cm from detectors are described. The sonde has a diameter of 60 mm and can be applied in wells with diameters of 76 to 350 mm. It is pressed to the sidewall during measurement. The determination of formation density from data measured with the two spacings is demonstrated by two examples considering perturbation parameters as borehole diameter, mud density, and the medium between tool and borehole wall.

Es werden die Konstruktionsprinzipien und die Einsatzparameter einer 4kanaligen Bohrlochmeβsonde zur gleichzeitigen Messung der natürlichen radioaktiven γ-Strahlung, des Kalibers der Bohrung und der rückgestreuten γ-Strahlung einer ¹³⁷Cs-Strahlungsquelle mit 15 und 35 cm Abstand zwischen Quelle und Deteklor vorgestellt. Mit 60 mm-Auβendurchmesser ist die Sonde in Bohrungen von 76 bis 350 mm Durchmesser einsetzbar; sie wird während der Meβfahrt an die Bohrlochwand angedrückt. Die Auswertemöglichkeiten der beiden Sondenlängen zur Bestimmung der Gebirgsdichte unter dem Einfluβ von Störparametern wie Bohrlochdurchmesser, Spülungsdichte und Zwischenmedium zwischen Bohrlochsonde und Bohrlochwand werden dargestellt und an zwei Meβbeispielen erläutert.     

Field Measurements of Radon Exhalation and Ra-226 Content in Soil using the Can-Technique

CR-39 and LR-115 plastic nuclear track detectors in the can-technique have been employed in the field measurements of radon exhalation, Ra-226 and U-238 content in dry-soil air at numerous regions in Sudan (the Blue and White Nile and Mogran regions). Measurements gave an average radon exhalation from the soil to the atmosphere and Ra-226 content of (23.4 ± 2.60) kBq · m^?2 and (123 ± 13.65) Bq · kg^?1 respectively. A polyethylene permeable membrane cover was used to eliminate the contribution of thoron activity inside the can. Assuming a radioactive equilibrium between the U-series, the average U-238 content in the soil was found to be (9.92 ± 1.01) ppm. This survey may be used for uranium prospection in soil.     

Road traffic noise - the relationship between noise exposure and noise annoyance in Norway

Exposure-effect relationships between the level of road traffic noise at the most exposed side of a dwelling's façade and the residents' reactions to road traffic noise have been estimated. The relationships are based on five Norwegian socio-acoustic studies featuring 18 study areas from two cities and a total of near 4000 respondents. The survey questionnaires distinguish between noise annoyance experienced right outside the apartment and when indoors. Exposure-effect relationships for all degrees of annoyance are estimated simultaneously from ordinal logit models. These predict road traffic noise annoyance when right outside the apartment and when indoors, respectively, as a function of the road traffic noise level outside the most exposed façade. Separate analyses indicate that Norwegians react stronger to road traffic noise than results from a recent compilation of socio-acoustic surveys would lead one to believe. People having inferior single glazing windows report higher indoor annoyance.     

A methodology to study noise annoyance and to perform Action Plans follow up using as input an existing survey and noise map: Application to the city of Málaga (Spain)

The main purpose of this work is to establish a methodology which uses the advantages of stratified sampling to study noise perception. Taking as a starting point the results of an existing psychosocial survey of a large population sample, the proposed procedure consists in stratifying the original sample into homogeneous groups (clusters or classes) as far as noise perception/annoyance, and then select some representatives within each group. Those representatives will be used for further inquiries relating to noise annoyance perception (i.e. action plans follow up) and may facilitate further data acquisition making it faster and cheaper to acquire without significant precision loss.According to the European Directive 2002/49/EC, action plans for noise perception and noise level conflicts reduction shall be based both on existing noise maps and existing psychosocial surveys. It is in this context that the proposed methodology can be useful, since it will allow action plans follow up and thus evaluate in a fast and cost effective way the impact of action plans on the population.The methodology has been applied to the Málaga psychosocial survey results and the variability of estimates when working with subsamples (representatives from each group) has been studied. It is observed that performing a stratified sampling technique on the clusters optimizes the cost/precision ratio of estimators.