Effect of distribution of fines on evolution of cooperation in spatial public goods game

In the realm of public goods game,punishment,as a potent tool,stands out for fostering cooperation.While it effectively addresses the first-order free-rider problem,the associated costs can be substantial.Punishers incur expenses in imposing sanctions,while defectors face fines.Unfortunately,these monetary elements seemingly vanish into thin air,representing a loss to the system itself.However,by virtue of the redistribution of fines to cooperators and punishers,not only can we mitigate this loss,but the rewards for these cooperative individuals can be enhanced.Based upon this premise,this paper introduces a fine distribution mechanism to the traditional pool punishment model.Under identical parameter settings,by conducting a comparative experiment with the conventional punishment model,the paper aims to investigate the impact of fine distribution on the evolution of cooperation in spatial public goods game.The experimental results clearly demonstrate that,in instances where the punishment cost is prohibitively high,the cooperative strategies of the traditional pool punishment model may completely collapse.However,the model enriched with fine distribution manages to sustain a considerable number of cooperative strategies,thus highlighting its effectiveness in promoting and preserving cooperation,even in the face of substantial punishment cost.

Fine Root Distribution Characteristics of Populus cathayana Plantations at Different Ages in Alpine Sandy Land

[Objectives]The paper was to study the fine root distribution characteristics of Populus cathayana plantations at different ages in alpine sandy land.[Methods]With 5,10,15,20,and 25 years old P.cathayana plantation in the eastern margin of Gonghe Basin,Qinghai Province as the research objects,fine roots were collected by root core drilling method,and the differences of fine root biomass,root length density,average diameter and root tip number at the soil depths of 0-20,20-40,40-60,60-80 and 80-100 cm were analyzed.[Results]The total biomass density of P.cathayana plantation was mainly distributed in the soil layer of 0-60 cm,accounting for 76%of the entire soil layer,and its value increased with the increase in forest age.With the increase in different forest ages,the root length density,average diameter and root tip number of living fine roots in the soil layer of 0-60 cm accounted for 74%-81%of the entire soil layer,and the proportions in the soil layers of 60-80 and 80-100 cm were 9%-11%.The biomass density,root length density,average diameter and root tip number of living and dead fine roots of P.cathayana plantation increased with the increase of forest age.The root length density,average diameter and root tip number of P.cathayana fine roots showed a linear function change trend with the growth of forest age,which could be described by the linear function equation y=ax+b(a>0).The analysis results showed that the root length density,average diameter and root tip number of P.cathayana were significantly correlated with the total biomass density of fine roots,and the root length density and average diameter had an extremely positive correlation with the total biomass density.[Conclusions]In the future,P.cathayana plantation should be properly tended to promote the development of fine roots and maximize its ecological benefits.

Nano-microbubble flotation of fine and ultrafine chalcopyrite particles

As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to improve flotation performance of fine and ultrafine particles, there is still much more to be done. In this paper, the effects of nano-microbubbles （nanobuhbles and microbubbles） on the flotation of fine （-38 ＋ 14.36 μm） and ultrafine （-14.36 ＋ 5μm） chalcopyrite particles were investigated in a laboratory scale Denver flotation cell. Nano-microbubbles were generated using a specially-designed nano- microbubble generator based on the cavitation phenomenon in Venturi tubes. In order to better under- stand the mechanisms of nano-microbubble enhanced froth flotation of fine and ultrafine chalcopyrite particles, the nano-microbubble size distribution, stability and the effect of frother concentration on nano- bubble size were also studied by a laser diffraction method. Comparative flotation tests were performed in the presence and absence of nano-microbubbles to evaluate their impact on the fine and ultrafine chalcopyrite particle flotation recovery. According to the results, the mean size of nano-microbubbles increased over time, and decreased with increase of frother concentration. The laboratory-scale flotation test results indicated that flotation recovery of chalcopyrite fine and ultrafine particles increased by approximately 16-21% in the presence of nano-microbubbles, depending on operating conditions of the process. The presence of nano-microbubbles increased the recovery of ultrafine particles （-14.36 ＋ 5 μm） more than that of fine particles （-38 ＋ 14.36 μm）. Another major advantage is that the use of nano-microbubbles reduced the collector and frother consumptions by up to 75% and 50%, respectively.

Polarimetric Study of the Fine Aerosol Fraction in Beijing

Measurements of aerosol optical characteris- tics were carried out with a Photoelectric Aerosol Nephelometer （PhAN） in Beijing and at Xinglong Obser- vatory, which is located 150 km northeast of Beijing. Aerosol size distributions were retrieved by means of the inverse problem solution. Mean volume size distributions of the fine aerosol fraction were unimodal with the maximum radius in the range 0.11-0.15 pm. Accumula- tion of aerosol matter in the air basin of Beijing takes place mainly due to the growth of particle size, but not their number. A simple optical method to detect aerosol nonsphericity is proposed.

Experimental and Modeling Study of the Regular Polygon Angle-spiral Liner in Ball Mills

Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners（RPASLs）, experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed： the energy input to the mill per unit mass of the fine product, E＊, and the rate of production of the fine product, F＊. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E＊ has the minimum value of 303 J per fine product and the production rate F＊ has the maximum value of 0.323. The production rate F＊ in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio Es/Et in the simulation. The relations between the production rate F＊ and the specific energy consumption E＊ with collision energy intensity Es and Et are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.