Positive Scale Effect Research Articles

Scaling approach towards electrochemical micromachining: a method to evaluate similarity

The electrochemical micromachining (ECMM) system is a modern equipment well thought out as the phenomenon of conventional electrochemical machining (ECM) system in microscale. The ECM system and ECMM system are similar, but the practice method and mechanism involved in the ECM system are analogous to those of the ECMM system, i.e., the differences in machining conditions and machining performance give rise to a factor called the scale effect. In this paper, ECMM has been applied with the advantageous concept called scale effect. Single factor experiments are conducted in which voltage, duty ratio, and tool feed rate are considered as the input factors for the exploration of the different grades of scale effect through the material removal rate, circularity, and overcut. The scale effects that occurred during machining are found using the similarity precision of the micro- and macrosystems based on the similarity theory. Quantitative evaluation of the scale effects is done for the ECMM process. The evaluation showed greater similarity precision indicating a larger significant scale effect. The output values of MRR, circularity, and overcut were normalized which also showed a positive scale effect. The research on scale effects delivers benefits in engineering such as optimizing the processing parameters involved and improving the machining performances of ECMM.

Numerical Shear Tests on the Scale Effect of Rock Joints under CNL and CND Conditions

The scale effect of rock joint shear behavior is an important subject in the field of rock mechanics. There is yet a lack of consensus regarding whether the shear strength of rock joints increases, decreases, or remains unchanged as the joint size increases. To explore this issue, a series of repeated and enlarged numerical joint models were established in this study using the particle flow code (PFC2D). The microparameters were calibrated by uniaxial compression tests and shear tests on the concrete material under the constant normal loading (CNL) condition. Three different normal stresses were adopted in numerical shear tests with joint specimen lengths ranging from 100 mm to 800 mm. In addition to the commonly used CNL, the constant normal displacement (CND) condition was established for the purposes of this study; the CND can be considered an extreme case of the constant normal stiffness (CNS) condition. The shear stress‐shear displacement curves changed from brittle failure to ductile failure alongside a gradual decrease in peak shear strength as joint length increased. That is, an overall negative scale effect was observed. Positive scale effect or no scale effect is also possible within a limited joint length range. A positive correlation was also observed between the peak shear displacement and joint length, and a negative correlation between shear stiffness and joint length. These above statements are applicable to both repeated and enlarged joints under either CNL or CND conditions. When the normal stress is sufficiently high and shear dilatancy displacement is very small, the shear behavior of rock joints under CNL and CND conditions seems to be consistent. However, for shear tests under low initial normal stress, the peak shear strength achieved under the CND condition is much higher than that under the CNL condition, as the normal stresses of enlarged joints increase to greater extent than the repeated ones during shearing.

A techno-economic-environmental study evaluating the potential of oxygen-steam biomass gasification for the generation of value-added products

The production of renewable chemicals and fuels is driving modern society towards a type of sustainable development which involves a decreasing dependency on fossil fuels and the minimisation of waste. Biomass, a waste by-product from the urban environment, is a carbon dioxide neutral organic fuel that can potentially serve as a feedstock for the production of sustainable power and heat. Gasification is preferred over the other thermal conversion options for biomass processing whereby the product synthesis gas can be utilised to power generators/turbines and generate clean energy, ammonia and methanol. Incidentally, efficient and economically sound biomass driven supply chains can be integrated into an existing petrochemical infrastructure. Moreover, the potential production volumes of fuels and green chemicals can also be increased by the addition of multiple biomass sources, thereby creating potential positive scale effects. This study proposes a new poly-generation process that utilises multiple sources of biomass feedstock to produce high quality urea, methanol, Fisher-Tropsch liquids and power. Four flowsheet configurations are simulated using Aspen Plus software and the built-in capabilities of the activated analysis using Aspen Process Economic Analyzer and Aspen Energy Analyzer to perform the economic, energy and environmental impact calculations. The results demonstrate that the methanol production technique is the most economic process pathway with a net profit of approximately $0.035 per kg of biomass input, whilst the urea process pathway presents the lowest environmental impact solution with approximately 0.71 kg of CO2-e per kg of biomass input. These results are relative and can be analysed from different perspectives based on the market demand of the products and their applications and local need. For instance, considering at the economic and environmental indicators relative to the production capacity, production of liquid fuels achieve net profits of approximately $0.27 per kg of product, whilst urea production demonstrates the lowest environmental emissions of approximately 3.93 kg of CO2-e per kg of product.

Multi-renewable management: Interactions between wind and solar within uncertain technology ecological system

By using stochastic Lotka-Volterra model, we make a cross-country analysis to potential interactions between penetrations of wind and photovoltaic (PV) technology within uncertain technology ecological systems, and explore the possible distributions of stochastic technology proliferation orbits. We find both positive and negative scale effects for wind markets, while PV solar markets are consistently scale-restrictive for all the target countries; the current technology interactions are dominated by mutualism and prey-predator types, of which prey-predator relationships mainly exist in the US, China and Italy, with PV solar to be predators. Most importantly, we find significant relationships between stochastic technology diffusion orbits and deterministic technology equilibrium orbit; specifically, random orbits of cumulative installed capacity for both wind and PV solar oscillate around the equilibrium orbit under the deterministic Lotka-Volterra model, normally distributed, and the mean orbit of such large-scale random orbits converges to the analytic equilibrium orbit. This finding makes great sense to identify countries with stable technology diffusion distributions, and contributes to exploit predictive features of stochastic Lotka-Volterra model. On this basis, we recognize 3 countries with normally distributed random orbits of technology penetration, i.e., India, Japan and Italy, and three-year forecasts to 2020 are provided for both wind and PV solar technology.

Evaluation of scale effect of micro electrical discharge machining system

Micro electrical discharge machining (EDM) is generally regarded as the application of conventional EDM in micro scale. The energy transfer characteristic and material removal mechanism of micro EDM are differ from that of macro EDM due to the miniaturization of tool electrode and discharge energy. The unexpected machining performance can be attributed to the so-called scale effect. In this study, the similarity theory was used to quantitatively evaluate the scale effect and the effectiveness of this evaluation method was established. In this method, greater similarity precision means more significant scale effect. Tool electrode diameter, capacitance, and open circuit voltage were adopted as factors in orthogonal experiment to explore the scale effect caused by the miniaturization of tool electrode and discharge energy. The single factor scale effect and system scale effect of EDM are evaluated based on orthogonal experiment. Scale effect with different degree is presented in terms of material removal rate (MRR), relative tool wear ratio (RTWR), and overcut (OC). The machining type is transferred from macro EDM to micro EDM as a result of the decrease of machining parameters. A positive scale effect is produced and open circuit voltage is the most important factor for the scale effect of EDM.

A step towards the end of the scale effect conundrum when predicting the shear strength of large in situ discontinuities

The shear strength of rock discontinuities is known to be scale dependent, and past research has revealed that both positive and negative scale effects could be observed. It is far from trivial to predict the occurrence of the scale effect and, to date, there is still no consensus on how to satisfactorily predict the shear strength of large discontinuities. A new stochastic approach was proposed and validated at laboratory scale by the authors. The approach consists of (1) using the information available from visible traces to create synthetic surfaces via a random field model and (2) estimating the shear strength of each one of the synthetic surfaces in order to obtain a distribution of shear strength and a mean shear strength. This paper presents the first application of this new approach to a large discontinuity that was surveyed with a resolution of 1 mm and an accuracy in the order of 150–230 µm in the Pilkington reserve of Newcastle, Australia. The paper first confirms that a scale effect does exist for the surface tested, before demonstrating that the new stochastic approach produces a strength envelope that is very close to the deterministic failure criterion of the whole surface. The key conclusion of this research is that there is enough information on visible traces, if surveyed accurately, to obtain an estimate of the shear strength of the discontinuity.

CONNECTIVITY AND ECONOMIC GROWTH

We present a simple theoretical model that illustrates the benefits of regional connectivity and specialization for growth. Starting with one community, we show how welfare measured by utility per head increases as the number of connected communities increases. We assume a common connectivity infrastructure through which a central planner is able to add new communities to the pool of already connected communities, a costly but rewarding activity that is funded by levying a tax on those already connected. We find that increasing production costs lead to faster transitions toward the steady state, whereas increasing transportation and communication costs tend to lengthen the transition. The results point to reductions in transportation and communication costs, in particular, as a suitable vehicle for speeding up growth and underline the existence of a positive scale effect that induces integration and reinforces both transitional and steady state growth.

Positive size and scale effects of all-cellulose composite laminates

Negative size effects are commonly reported for advanced composite materials where the strength of the material decreases with increasing volume of the test specimen. In this work, the effect of increasing specimen volume on the mechanical properties of all-cellulose composites is examined by varying the laminate thickness. A positive size effect is observed in all-cellulose composite laminates as demonstrated by a 32.8% increase in tensile strength as the laminate thickness is increased by 7 times. The damage evolution in all-cellulose composite laminates was examined as a function of the tensile strain. Enhanced damage tolerance concomitant with increasing specimen volume is associated with damage accumulation due to transverse cracking and strain delocalisation. A transition from low-strain failure to tough and high-strain failure is observed as the laminate thickness is increased. Simultaneously, scale effects lead to an increase in the void content and cellulose crystallinity at the core, with increasing laminate thickness.

Are Fast Responses More Random? Testing the Effect of Response Time on Scale in an Online Choice Experiment

Scepticism over stated preference surveys conducted online revolves around the concerns over “professional respondents” who might rush through the questionnaire without sufficiently considering the information provided. To gain insight on the validity of this phenomenon and test the effect of response time on choice randomness, this study makes use of a recently conducted choice experiment survey on ecological and amenity effects of an offshore windfarm in the UK. The positive relationship between self-rated and inferred attribute attendance and response time is taken as evidence for a link between response time and cognitive effort. Subsequently, the generalised multinomial logit model is employed to test the effect of response time on scale, which indicates the weight of the deterministic relative to the error component in the random utility model. Results show that longer response time increases scale, i.e. decreases choice randomness. This positive scale effect of response time is further found to be non-linear and wear off at some point beyond which extreme response time decreases scale. While response time does not systematically affect welfare estimates, higher response time increases the precision of such estimates. These effects persist when self-reported choice certainty is controlled for. Implications of the results for online stated preference surveys and further research are discussed.

Effects of amisulpride on the cognitive function in first-episode schizophrenia patients

Objective To explore the effects of amisulpride on the cognitive function in first-episode schizophrenia patients. Methods 64 patients in first-episode schizophrenia were divided into two groups randomly according to the method of tossing a coin, then treated with amisulpride or risperidone respectively for 12 weeks.The efficacy and adverse effect were evaluated with positive and negative scale (PANSS) and treatment emergent side effect scale (TESS) before treatment and after treatment for 2 weeks, 4 weeks, 8 weeks, 12 weeks.Before and after treatment for 12 weeks, cognitive function of all the patients was blindly evaluated with Wechsler Scale-revised China (WMS-RC) , Wisconsin Card Sorting Test(WCST)and Trail Making test A and B. Results After 12-week treatment, statistical difference was found in amisulpride(44.7±6.7) and risperidone(45.2±7.4) groups (P 0.05). The cognitive function in first-episode schizophrenia was damaged obviously.In two groups, the scores in recognize, association, comprehend, back a few and MQ of WMS and TAT-A, TAT-B were improved significantly after treatment for 12 weeks(P>0.05). These items of WCST were improved more remarkably than baseline (amisulpride(20.63±13.06), (28.75±15.72), (43.17±22.13), (3.62±2.21), P 0.05). Conclusion The study shows that the cognitive dysfunction in first-episode schizophrenia can be improved by amisulpride, and the efficacy was similar with risperidone. Key words: Amisulpride; Risperidone; Schizophrenia; Cognitive function

Ondansetron and simvastatin added to treatment as usual in patients with schizophrenia: study protocol for a randomized controlled trial

BackgroundNegative symptoms and cognitive deficits are two partially-related features of schizophrenia which have a major negative impact on social function and objective quality of life. Standard drug treatments have little impact on either. There is some evidence that anti-inflammatory treatment may have beneficial effects in schizophrenia and major depression. Statins are cholesterol-lowering agents that have been found to be anti-inflammatory agents and are also known to decrease C-reactive protein (CRP). Ondansetron is a serotonin (5-HT3) receptor antagonist widely used to prevent nausea and vomiting in patients receiving chemotherapy for cancer. Small studies have suggested that ondansetron is effective as an adjunct drug in improving the symptoms of schizophrenia.Methods/designThis is a two center, six-month, double-blind placebo controlled, factorial design study of ondansetron and/or simvastatin added to treatment as usual for patients suffering from schizophrenia, schizoaffective disorder, psychosis not otherwise specified or schizophreniform disorder. This will be a 2 × 2 design, with 54 patients in each cell, giving a total of 216 patients over three years. There will be a screening, a randomization and seven follow-up visits. Full clinical and neurocognitive assessments will be carried out at baseline (randomization), 14 weeks and at 26 weeks, while the positive and negative syndrome scale (PANSS), pill count and side effects checklist will be carried out at every visit. Simvastatin will be started at 20 mg once daily (OD), this will be increased to 40 mg after four weeks. Ondansetron will be administered in an 8 mg dose.DiscussionAnti-inflammatory treatments have been shown to have some beneficial effects in schizophrenia. Both simvastatin and ondansetron provide some evidence of a reduction in symptoms compared to treatment as usual. The aim of this study is to establish the degree of improvement in negative symptoms with the addition of ondansetron and/or simvastatin to treatment as usual.Trail registrationClinicalTrails.gov NCT01602029

Technology Diffusion and Environmental Regulation: The Adoption of Scrubbers by Coal-Fired Power Plants

Title IV of the 1990 Clean Air Act Amendments implemented a pollution permit system for sulfur dioxide (SO2) emissions that departs from state command-and-control regulations that were in place prior to and during its implementation. This paper develops a technology diffusion model, relying on rank effects or firm heterogeneity, to explain the adoption of scrubbers, a SO2 abatement technology. Using survival analysis, empirical results show that generating units regulated under Phase I of Title IV, units facing more stringent state regulations, and units with low expected installation costs are much more likely to install a scrubber. In addition, there is evidence of positive scale effects of adoption, meaning larger units are more likely to adopt because expected installation costs are lower. Tradable permit systems should give firms more flexibility in choosing abatement technologies, but results show that when command-and-control regulations overlap with a market-based system, the technology choice is restricted. http://dx.doi.org/10.5547/01956574.34.1.8

Environmental effects of foreign trade and its spatial variations in mid-eastern provinces and cities of China

The studies on environmental effects of foreign trade and its spatial variations are helpful to design and implement environmental protection countermeasures. In order to eliminate the adverse effects of insufficient observation values on the accuracy of regression results and dynamic information quantity of fitting equation during empirical study, panel data of the mid-eastern provinces and cities of China from 1985 to 2007 were selected based on the adjustment of classical regression model in this paper. Panel unit root test and panel cointegration analysis method were applied to investigating the environmental effects of foreign trade and its spatial variations in the mid-eastern provinces and cities of China and its three groups divided by foreign trade dependence. The results show that all scale effects are positive, while all technical effects are negative and unable to counteract positive scale effects. Foreign trade development is regarded as an important cause for outstanding eco-environmental problems in the mid-eastern provinces and cities of China. Total effects and structural effects are significantly different among different groups because of spatial variations in environmental policies, export destinations, source of FDI, etc. Following the principle of ‘coordinating generality and considering differences comprehensively’, it is essential to issue a series of policies and countermeasures corresponding to differences in regional environmental effect of foreign trade, in order to coordinate the relationship between foreign trade development and eco-environment in each region.

Learning by exporting: Lessons from high-technology SMEs

We investigate the learning by exporting hypothesis by examining the effect of exporting on the subsequent innovation performance of a sample of high-technology SMEs based in the UK. We find evidence of learning by exporting, but the pattern of this effect is complex. Exporting helps high-tech SMEs innovate subsequently, but does not make them more innovation intensive. There is evidence that consistent exposure to export markets helps firms overcome the innovation hurdle, but that there is a positive scale effect of exposure to export markets which allows innovative firms to sell more of their new-to-market products on entering export markets. Service sector firms are able to reap the benefits of exposure to export markets at an earlier (entry) stage of the internationalization process than are manufacturing firms. Innovation-intensive firms exhibit a different pattern of entry to and exit from export markets from low-intensity innovators, and this is reflected in different effects of exporting.

Scale, Scope, Ownership Changes, and Performance

Estimating how scale and scope affect the performance of multi-product firms has been a challenge. We argue that because franchised chains are fundamentally single-product entities, we can use data on franchised chains and their parents to clearly distinguish scale and scope, and assess their effects, and those of ownership changes, on chain performance. Controlling for chain fixed effects and other factors; we find positive scale effects within chains. For parent company scope (the number of other chains of the parent) we find a negative rather than positive effect. We also find a reduction in the chain’s number of outlets, but no change in sales per outlet, after a chain is acquired by a new parent. Overall, our results suggest that acquisitions are disruptive, as multi-chain parents try to reduce competition among their chains/products.

Endogenous growth and adverse selection in entrepreneurship

This paper proposes a model of Schumpeterian endogenous growth incorporating the role of market imperfections that exist due to adverse selection between investors that finance R&D and entrepreneurs that perform R&D. There is a distribution of agents indexed by a skill factor that determines one's average productivity at performing research. An entrepreneur starts-up a research venture by borrowing from an investor that funds R&D so as to invent new goods. Skill is private information, creating an adverse selection problem for the investor who designs a truth-telling mechanism. We show that an increase in the mean skill enhances growth as it leads to greater R&D productivity and investment; while an increase in the dispersion of the skill distribution dampens growth as it makes the adverse selection problem between investors and entrepreneurs more severe. The growth rate would double in the absence of adverse selection. The R&D investment of the average size firm must be subsidized threefold for the negative adverse selection effect to be nullified. We provide U.S. industry-level and European sector-level evidence in favor of the positive scale effect and negative adverse selection effect using the firm size distribution (FSD) to proxy for the entrepreneurial skill distribution.

Analysis of Scale Effects in Peer-to-Peer Networks

In this paper, we study both positive and negative scale effects on the operations of peer-to-peer (P2P) file sharing networks and propose the optimal sizing (number of peers) and grouping (number of directory intermediary) decisions. Using analytical models and simulation, we evaluate various performance metrics to investigate the characteristics of a P2P network. Our results show that increasing network scale has a positive effect on the expected content availability and transmission cost, but a negative effect on the expected provision and search costs. We propose an explicit expression for the overall utility of a content sharing P2P community that incorporates tradeoffs among all of the performance measures. This utility function is maximized numerically to obtain the optimal network size (or scale). We also investigate the impact of various P2P network parameters on the performance measures as well as optimal scaling decisions. Furthermore, we extend the model to examine the grouping decision in networks with symmetric interconnection structures and compare the performance between random- and location-based grouping policies.

A Comparative Analysis of the EU-Morocco FTA vs. Multilateral Liberalization

An applied general equilibrium model with oligopoly and scale economies, based on detailed plant-level data, is used to contrast the impacts of the Morocco-EU free trade area (FTA) to multilateral trade liberalization on Morocco’s economy. Simulation results show that the FTA agreement is likely to have adverse effects on Morocco due to: (a) deteriorating terms of trade, (b) reductions in output per firm in industries dominated by scale economies, (c) diversion of imports away from relatively low cost, non-EU suppliers, and (d) potentially adverse effects on the aggregate demand for labor which could exacerbate already high levels of unemployment. We contrast this FTA with a multilateral liberalization scenario along the lines of those proposed under the Doha Development Round and find this to be more beneficial to Morocco, despite the associated income transfer from the EU to Morocco. The difference may be attributed to: (a) lesser terms of trade losses, (b) positive scale effects, (c) non-preferential liberalization of imports into Morocco, and (d) a positive impact on aggregate labor demand and hence unemployment. We conclude that Morocco would be better off pursuing trade liberalization in the multilateral arena. JEL classification: F12, F14, F15 Keywords: Applied general equilibrium; Market Structure; Trade liberalization; Developing economies; Morocco

Nonmarket networks among migrants: evidence from metropolitan Bangkok, Thailand

This paper examines the nonmarket interactions among migrants in the urban labor market of Bangkok, Thailand. We test whether the population size and the labor-market performance of previous migrants have externalities to new migrants who have moved from the same province of origin. Our empirical results, which control origin fixed effects, time fixed effects, and origin- and year-specific correlated shocks, show that (1) the relative population size of previous migrants in the market decreases the employment probability of new migrants (substitution effect), (2) the employment probability of previous migrants increases that of new migrants (positive externalities), and (3) when the employment probability of previous migrants is high, however, the scale effect becomes positive, which demonstrates a threshold in the informational scale economies. The results imply that positive informational scale effect dominates negative substitution effect when the efficiency of previous migrants is sufficiently high in the destination labor market.

An insurance paradox

Purpose – To consider why the law of large numbers does not play a more significant role in determining an insurer's financial leverage.Design/methodology/approach – Insurer‐group data show that there is little relationship between an insurer's premium volume and its overall leverage (i.e. net written premium‐to‐surplus ratio). An explanation is sought for the lack of a positive scale effect by considering concomitant negative scale effects.Findings – It is argued that insurers frequently convert the benefits of the law of large numbers into economic subsidies for expanded writings that include poorer risks.Originality/value – The editorial identifies and explores a significant scale phenomenon in the insurance sector that is generally overlooked.