Low area field-programmable gate array implementation of PRESENT image encryption with key rotation and substitution

Lightweight ciphers are increasingly employed in cryptography because of the high demand for secure data transmission in wireless sensor network, embedded devices, and Internet of Things. The PRESENT algorithm as an ultra-lightweight block cipher provides better solution for secure hardware cryptography with low power consumption and minimum resource. This study generates the key using key rotation and substitution method, which contains key rotation, key switching, and binary-coded decimal-based key generation used in image encryption. The key rotation and substitution-based PRESENT architecture is proposed to increase security level for data stream and randomness in cipher through providing high resistance to attacks. Lookup table is used to design the key scheduling module, thus reducing the area of architecture. Field-programmable gate array (FPGA) performances are evaluated for the proposed and conventional methods. In Virtex 6 device, the proposed key rotation and substitution PRESENT architecture occupied 72 lookup tables, 65 flip flops, and 35 slices which are comparably less to the existing architecture.     

Syngas production from chemical looping gasification of rice husk-derived biochar over iron-based oxygen carriers modified by different alkaline earth metals

Oxygen carrier (OC) is a key factor in chemical looping gasification (CLG). Iron oxide is a promising OC due to advantages regarding cost and environment; however, its reactivity with biochar requires improvement to increase syngas production. The novelty of this work is to compare the performance of alkaline earth metals (AEMs: Ca, Ba, and Mg) ferrites and iron oxide OCs for enhancing syngas production from CLG of biochar. The thermogravimetric analyzer and fixed bed system were used to investigate OCs performance. The results demonstrated that the AEMs ferrites have good gasification performance, and BaFe₂O₄ showed highest syngas yield through solid-solid reaction. Furthermore, CLG was conducted under steam addition, and the results revealed that all AEMs ferrites had improved the performance compared to iron oxide, as syngas yield increased by 39.2%, 15.7%, and 13.8% for BaFe₂O₄, CaFe₂O₄, and MgFe₂O₄, respectively. The highest syngas produced by BaFe₂O₄ reached 0.07 mol/g of biochar.     

基于DSP技术的配电房关键位置温度测量系统

目前配电房关键位置温度测量系统未设计温度智能标定程序,导致系统温度测量精度和正确率较低,为此提出设计基于DSP技术的配电房关键位置温度测量系统。硬件方面,考虑系统核心模块和测量性能,优化系统硬件结构和显示模块。软件方面,设计系统温度采集模块,采集配电房关键位置温度,设计温度测算程序和温度智能标定程序,智能测量配电房关键位置温度。实验结果表明:该系统受到外界温度因素影响较小,拟合曲线拟合度较高,具有较高的温度测量精度和正确率。     

资源循环利用对有色金属工业发展的影响

资源循环利用是把全社会已经使用过的物品、边角料、废弃物作为一种资源,经过技术处理重新服务于人类。而循环经济则是一种新的经济模型。资源循环利用对有色金属工业可持续发展意义重大,值得深入研究。本文对有色金属资源循环的必要性及资源循环型社会建立的条件进行了初步分析,以期引起人们的思考。     

On metal desorption and brucite regeneration

The data on metal desorption from brucite surface under the action of acid and alkaline dissolvents are reported. The desorption process is found to associate with the regeneration of a sorbent along with the substantial improvement of its sorption capacity. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh No. 5, pp. 115–119, September–October, 2006.     

几种浮选尾矿重金属释放的对比与分析

对几种选矿尾矿的净产酸潜力 (NAPP)、酸中和能力 (ANC)以及净产酸量 (NAG)进行测定 ,考查尾矿酸化后的重金属释放情况。矿物组成、选矿工艺与尾矿的产酸能力、重金属的释放有明显的相关性。     

河北某稀有多金属矿选矿试验研究

河北省某碱性长石花岗岩铷矿,稀有金属以铷为主,伴生有锂、铯、铌、钽。铷和铯以类质同象的形式赋存于钾长石和铁锂云母中,锂主要以铁锂云母形式存在。铌钽主要以独立矿物存在于铌钽铁矿中。采用"弱磁-强磁-浮选云母-长石石英分离"的联合选矿工艺流程,最终可获得Nb_2O_5品位3 241g/t、Ta_2O_5品位1 091g/t、Nb_2O_5回收率54.32%、Ta_2O_5回收率45.45%的铌钽铁精矿。Rb_2O品位11 941g/t、Li_2O品位25 220g/t、Cs_2O品位2 265g/t、Rb_2O回收率28.51%、Li_2O回收率75.89%、Cs_2O回收率54.77%的云母精矿。Rb_2O品位2 276g/t、Rb_2O回收率54.58%的长石精矿以及SiO_2品位98%以上的石英精矿。回收铷等稀有金属矿的同时,云母、长石、石英亦得到了分选回收与综合利用。     

贵金属资源及供需形势

本文详细的分析了世界金属资源及供需形势。     

预制屋面工程防水密封技术措施

介绍了导致屋面结构层变形的原因及变形量的计算方法,指出屋面防水必须对屋面接缝部位采取重点防护措施,才能经济、有效地防止屋面渗漏,并对重点防护部位的细部构造与施工技术要点进行了论述。