Quantity, Not Quality: An Analysis of China's Food Demand in Terms of Physical Quantity Rather than Quality

2012 ◽  
Author(s):  
Taro Takahashi
2014 ◽  
Vol 701-702 ◽  
pp. 246-249
Author(s):  
Sai Tan ◽  
Jun Yong Lu ◽  
Xin Lin Long ◽  
Xiao Zhang

Basing on governing Maxwell and energy equation of rail gun considering armature movement in two dimension, The total domain to be solved is divided into two subdomains: moving (armature) part and static (rail) part, finite element formulations of two subdomains are built independently, then using the interface condition of two subdomains, formulations are connected by coupled equation which is derived out by penalty method. Shifted physical quantity is used to simulate movement. The final magnetic-thermal coupled fields finite element formulations of rail gun are established by these methods. Numerical calculation results compared by theoretical and other numerical results verify that penalty method is an effective way to deal with electric sliding contact problem associating with Shifted physical quantity method.


Agronomy ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 214 ◽  
Author(s):  
Jagadish Timsina

Meeting global demand of safe and healthy food for the ever-increasing population now and into the future is currently a crucial challenge. Increasing crop production by preserving environment and mitigating climate change should thus be the main goal of today’s agriculture. Conventional farming is characterized by use of high-yielding varieties, irrigation water, chemical fertilizers and synthetic pesticides to increase yields. However, due to either over- or misuse of chemical fertilizers or pesticides in many agro-ecosystems, such farming is often blamed for land degradation and environmental pollution and for adversely affecting the health of humans, plants, animals and aquatic ecosystems. Of all inputs required for increased agricultural production, nutrients are considered to be the most important ones. Organic farming, with use of organic sources of nutrients, is proposed as a sustainable strategy for producing safe, healthy and cheaper food and for restoring soil fertility and mitigating climate change. However, there are several myths and controversies surrounding the use of organic versus inorganic sources of nutrients. The objectives of this paper are: (i) to clarify some of the myths or misconceptions about organic versus inorganic sources of nutrients and (ii) to propose alternative solutions to increase on-farm biomass production for use as organic inputs for improving soil fertility and increasing crop yields. Common myths identified by this review include that organic materials/fertilizers can: (i) supply all required macro- and micro-nutrients for plants; (ii) improve physical, chemical and microbiological properties of soils; (iii) be applied universally on all soils; (iv) always produce quality products; (v) be cheaper and affordable; and (vi) build-up of large amount of soil organic matter. Other related myths are: “legumes can use entire amount of N2 fixed from atmosphere” and “bio-fertilizers increase nutrient content of soil.” Common myths regarding chemical fertilizers are that they: (i) are not easily available and affordable, (ii) degrade land, (iii) pollute environment and (iv) adversely affect health of humans, animals and agro-ecosystems. The review reveals that, except in some cases where higher yields (and higher profits) can be found from organic farming, their yields are generally 20–50% lower than that from conventional farming. The paper demonstrates that considering the current organic sources of nutrients in the developing countries, organic nutrients alone are not enough to increase crop yields to meet global food demand and that nutrients from inorganic and organic sources should preferably be applied at 75:25 ratio. The review identifies a new and alternative concept of Evergreen Agriculture (an extension of Agroforestry System), which has potential to supply organic nutrients in much higher amounts, improve on-farm soil fertility and meet nutrient demand of high-yielding crops, sequester carbon and mitigate greenhouse gas emissions, provide fodder for livestock and fuelwood for farmers and has potential to meet global food demand. Evergreen Agriculture has been widely adapted by tens of millions of farmers in several African countries and the review proposes for evaluation and scaling-up of such technology in Asian and Latin American countries too.


2007 ◽  
Vol 39 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Baichen Jiang ◽  
John Davis

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