Browsing by Author "Liu, Wei"

Now showing 1 - 8 of 8
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    Breaking Down Network Slicing: Hierarchical Orchestration of End-to-End Networks
    Santos, Joao F.; Liu, Wei; Jiao, Xianjun; Neto, Natal V.; Pollin, Sofie; Marquez-Barja, Johann M.; Moerman, Ingrid; DaSilva, Luiz A. (IEEE, 2020-10-01)
    Network slicing is one of the key enabling techniques for 5G, allowing Network Providers (NPs) to support services with diverging requirements on top of their physical infrastructure. In this paper, we address the limited support and oversimplified resource allocation on different network segments of existing End-to-End (E2E) orchestration solutions. We propose a hierarchical orchestration scheme for E2E networks, breaking down the E2E resource management and network slicing problems per network segment. We introduce a higherlevel orchestrator, the hyperstrator, to coordinate the distributed orchestrators and deploy Network Slices (NSs) across multiple network segments. We developed a prototype implementation of the hyperstrator and validated our hierarchical orchestration concept with two proof-of-concept experiments, showing the NS deployment and the impact of the resource allocation per network segment on the performance of NSs. The results show that the distributed nature of our orchestration architecture introduces negligible overhead for provisioning NSs in our particular setting, and confirm the need of a hyperstrator for coordinating network segments and ensuring consistent QoS for NSs.
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    Building A Fast and Efficient LSM-tree Store by Integrating Local Storage with Cloud Storage
    Xu, Peng; Zhao, Nannan; Wan, Jiguang; Liu, Wei; Chen, Shuning; Zhou, Yuanhui; Albahar, Hadeel; Liu, Hanyang; Tang, Liu; Tan, Zhihu (ACM, 2022-05-25)
    The explosive growth of modern web-scale applications has made cost-effectiveness a primary design goal for their underlying databases. As a backbone of modern databases, LSM-tree based key-value stores (LSM store) face limited storage options. They are either designed for local storage that is relatively small, expensive, and fast or for cloud storage that offers larger capacities at reduced costs but slower. Designing an LSM store by integrating local storage with cloud storage services is a promising way to balance the cost and performance. However, such design faces challenges such as data reorganization, metadata overhead, and reliability issues. In this paper, we propose RocksMash, a fast and efficient LSM store that uses local storage to store frequently accessed data and metadata while using cloud to hold the rest of the data to achieve cost-effectiveness. To improve metadata space-efficiency and read performance, RocksMash uses an LSM-aware persistent cache that stores metadata in a space-efficient way and stores popular data blocks by using compaction-aware layouts. Moreover, RocksMash uses an extended write-ahead log for fast parallel data recovery. We implemented RocksMash by embedding these designs into RocksDB. The evaluation results show that RocksMash improves the performance by up to 1.7x compared to the state-of-the-art schemes and delivers high reliability, cost-effectiveness, and fast recovery.
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    Effects of Individual Essential Amino Acids on Growth Rates of Young Rats Fed a Low-Protein Diet
    Liu, Wei; Wang, Tianyi; Zhao, Kai; Hanigan, Mark D.; Lin, Xueyan; Hu, Zhiyong; Hou, Qiuling; Wang, Yun; Wang, Zhonghua (MDPI, 2024-03-20)
    To investigate the effects of individual essential amino acids (EAA) on growth and the underlying mechanisms, EAA individually supplemented a low-protein (LP) diet fed to young rats in the present study. Treatments were an LP diet that contained 6% crude protein (CP), a high-protein (HP) diet that contained 18% CP, and 10 LP diets supplemented with individual EAA to achieve an EAA supply equal to that of the HP diet. The CP concentration of the LP diet was ascertained from the results of the first experiment, which examined the effects of dietary CP concentrations on growth rates, with CP ranging from 2% to 26%. Weight gain was increased with the supplementation of His, Ile, Lys, Thr, or Trp as compared to the LP diet (p < 0.05). Feed intake was greater for the His-, Lys-, and Thr-supplemented treatments as compared to the LP group (p < 0.05). Protein utilization efficiency was lower for the HP group than other groups (p < 0.01). The supplementation of Leu, Lys, and Val led to reduced protein utilization efficiency (p < 0.05), but the supplementation of Thr and Trp led to greater efficiency than the LP group (p < 0.05). Compared to the LP group, plasma urea concentrations were elevated with individual EAA supplementation, with the exception of the Thr addition. The added EAA resulted in increased concentrations of the corresponding EAA in plasma, except for Arg and Phe supplementation. The supplementation of Arg, His, Leu, Lys, and Met individually stimulated mTORC1 pathway activity (p < 0.05), and all EAA resulted in the decreased expression of ATF4 (p < 0.05). In summary, the supplementation of His, Ile, Lys, Thr, or Trp to an LP diet improved the growth performance of young rats. Responses to His and Lys additions were related to the activated mTORC1 pathway and feed intake increases. The improved growth performance resulting from the addition of a single EAA is not solely attributed to the increased plasma availability of EAA. Rather, it may be the consequence of a confluence of factors encompassing signaling pathways, the availability of amino acids, and other associated elements. The additivity of these factors results in independent responses to several EAA with no order of limitation, as is universally encoded in growth models for all production animal species.
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    Genome sequences of wild and domestic bactrian camels
    Jirimutu; Wang, Zhen; Ding, Guohui; Chen, Gangliang; Sun, Yamin; Sun, Zhihong; Zhang, Heping; Wang, Lei; Hasi, Surong; Zhang, Yan; Li, Jianmei; Shi, Yixiang; Xu, Ze; He, Chuan; Yu, Siriguleng; Li, Shengdi; Zhang, Wenbin; Batmunkh, Mijiddorj; Ts, Batsukh; Narenbatu; Unierhu; Bat-Ireedui, Shirzana; Gao, Hongwei; Baysgalan, Banzragch; Li, Qing; Jia, Zhiling; Turigenbayila; Subudenggerile; Narenmanduhu; Wang, Zhaoxia; Wang, Juan; Pan, Lei; Chen, Yongcan; Ganerdene, Yaichil; Dabxilt; Erdemt; Altansha; Altansukh; Liu, Tuya; Cao, Minhui; Aruuntsever; Bayart; Hosblig; He, Fei; Zha-ti, A.; Zheng, Guangyong; Qiu, Feng; Sun, Zikui; Zhao, Lele; Zhao, Wenjing; Liu, Baohong; Li, Chao; Chen, Yunqin; Tang, Xiaoyan; Guo, Chunyan; Liu, Wei; Ming, Liang; Temuulen; Cui, Aiying; Li, Yi; Gao, Junhui; Li, Jing; Wurentaodi; Niu, Shen; Sun, Tao; Zhai, Zhengxiao; Zhang, Min; Chen, Chen; Baldan, Tunteg; Bayaer, Tuman; Li, Yixue; Meng, He (Springer Nature, 2012-11)
    Bactrian camels serve as an important means of transportation in the cold desert regions of China and Mongolia. Here we present a 2.01 Gb draft genome sequence from both a wild and a domestic bactrian camel. We estimate the camel genome to be 2.38 Gb, containing 20,821 protein-coding genes. Our phylogenomics analysis reveals that camels shared common ancestors with other even-toed ungulates about 55-60 million years ago. Rapidly evolving genes in the camel lineage are significantly enriched in metabolic pathways, and these changes may underlie the insulin resistance typically observed in these animals. We estimate the genome-wide heterozygosity rates in both wild and domestic camels to be 1.0 x 10(-3). However, genomic regions with significantly lower heterozygosity are found in the domestic camel, and olfactory receptors are enriched in these regions. Our comparative genomics analyses may also shed light on the genetic basis of the camel's remarkable salt tolerance and unusual immune system.
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    Mandate-driven Networking Eco-system: A Paradigm Shift in End-to-End Communications
    Moerman, Ingrid; Zeghlache, Djamal; Shahid, Adnan; Santos, Joao F.; DaSilva, Luiz A.; David, Klaus; Farscrotu, John; de Ridder, Ad; Liu, Wei; Hoebeke, Jeroen (IEEE, 2020-01-01)
    The wireless industry is driven by key stakeholders that follow a holistic approach of “one-system-fits-all” that leads to moving network functionality of meeting stringent End-to- End (E2E) communication requirements towards the core and cloud infrastructures. This trend is limiting smaller and new players for bringing in new and novel solutions. For meeting these E2E requirements, tenants and end-users need to be active players for bringing their needs and innovations. Driving E2E communication not only in terms of quality of service (QoS) but also overall carbon footprint and spectrum efficiency from one specific community may lead to undesirable simplifications and a higher level of abstraction of other network segments may lead to sub-optimal operations. Based on this, the paper presents a paradigm shift that will enlarge the role of wireless innovation at academia, Small and Medium-sized Enterprises (SME)’s, industries and start-ups while taking into account decentralized mandate-driven intelligence in E2E communications.
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    De novo Transcriptome Analysis and Molecular Marker Development of Two Hemarthria Species
    Huang, Xiu; Yan, Haidong; Zhang, Xinquan; Zhang, Jian; Frazier, Taylor P.; Huang, Dejun; Lu, Lu; Huang, Linkai; Liu, Wei; Peng, Yan; Ma, Xiao; Yan, Yan-Hong (Frontiers, 2016-04-18)
    Hemarthria R. Br. is an important genus of perennial forage grasses that is widely used in subtropical and tropical regions. Hemarthria grasses have made remarkable contributions to the development of animal husbandry and agro-ecosystem maintenance; however, there is currently a lack of comprehensive genomic data available for these species. In this study, we used Illumina high-throughput deep sequencing to characterize of two agriculturally important Hemarthria materials, H. compressa "Yaan" and H. altissima "1110." Sequencing runs that used each of four normalized RNA samples from the leaves or roots of the two materials yielded more than 24 million high-quality reads. After de novo assembly, 137,142 and 77,150 unigenes were obtained for "Yaan" and "1110," respectively. In addition, a total of 86,731 "Yawn" and 48,645 "1110" unigenes were successfully annotated. After consolidating the unigenes for both materials, 42,646 high-quality SNPs were identified in 10,880 unigenes and 10,888 SSRs were identified in 8330 unigenes. To validate the identified markers, high quality PCR primers were designed for both SNPs and SSRs. We randomly tested 16 of the SNP primers and 54 of the SSR primers and found that the majority of these primers successfully amplified the desired PCR product. In addition, high cross-species transferability (61.11-87.04%) of SSR markers was achieved for four other Poaceae species. The amount of RNA sequencing data that was generated for these two Hemarthria species greatly increases the amount of genomic information available for Hemarthria and the SSR and SNP markers identified in this study will facilitate further advancements in genetic and molecular studies of the Hemarthria genus.
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    Rare Earth Extraction from Clayey Waste Materials by Alkali Pretreatment
    Liu, Wei (Virginia Tech, 2023-04-12)
    The increasing demand for rare earth elements (REEs) and the depletion of conventional rare earth deposits have enabled secondary REE resources to be promising feedstocks for REEs. Studies have been conducted in developing technologies that can physically preconcentrate and/or chemically extract REEs from low-REE-grade clayey waste materials (e.g., coal-based clays). However, the low REE grades and poor leachability of REE-bearing species still make the recovery of REEs from coal-based clays challenging. The primary objective of this study is to develop leaching technologies that can extract REEs from clayey waste materials under mild conditions (<100 oC). In the first part of this work, a novel leaching process consisting of NaOH pretreatment followed by ammonium sulfate leaching has been proposed to recover REEs from monazite, which served as a proxy for the rare earth phosphates identified in coal-based clays. In this process, monazite can be decomposed at 80 oC. The following ammonium sulfate leaching was conducted under less aggressive conditions (i.e., pH 4 and room temperature) to recover REEs. After releasing RE3+ ions from RE(OH)3(s) by acid, the role of ammonium sulfate in the leaching process may be explained by an ion exchange mechanism. Sulfate ions also benefit the leaching process by complexing with RE3+ ions. The influences of temperature and particle size on the leaching kinetics of REEs from the NaOH-treated monazite by ammonium sulfate were also investigated based on the shrinking core model. It was found that the leaching process is controlled by a chemical reaction with an activation energy of 61.28 kJ/mol. Besides ammonium sulfate, ammonium formate is a promising lixiviant for NaOH-treated monazite. However, other carboxylate ligands tested were inefficient at room temperature, mainly due to the slow dissolution kinetics of RE(OH)3(s) resulting from the passivation of the binuclear surface complexes. Subsequently, the feasibility of decomposing rare earth phosphates by NaOH in the presence of ethylenediaminetetraacetic acid (EDTA) was explored by constructing the stability diagrams for La-, Nd-, and Y-PO4-H2O systems, respectively. The simulation results were validated using three coal-based clay samples. The leaching results of both HCl and ammonium sulfate indicated that the pretreatment conducted by combining EDTA with dilute NaOH solutions (5-10%) could significantly enhance the REE leachability of the clay samples, with the light REEs (LREEs) being preferentially extracted compared to heavy REEs (HREEs). Under optimal conditions, the co-extraction of Al and Si can be significantly reduced. Besides liberated phosphate mineral particles, X-Ray photoelectron spectroscopy (XPS) analyses conducted on the synthetic ion adsorption clay samples revealed that phosphate could also passivate the REEs adsorbing on the surface of clay minerals in the form of “clay-RE-PO4”. This finding may partially explain the poor ion exchangeability of REEs in coal-based clays. After subjecting to the proposed NaOH pretreatment technique, the passivated REEs on the surface of clay can be effectively removed. Lastly, the possibility of preconcentrating REEs from a kaolinite flotation reject material was explored by froth flotation and the hydrophobic-hydrophilic separation (HHS). A final concentrate assaying 10,765 ppm of REEs and 71% of recovery was obtained by the HHS process, which was superior to flotation in dealing with ultrafine particles. The microscopic characterization of the concentrate revealed that rare earth phosphates were the major REE-bearing species. The leaching results showed that the proposed NaOH pretreatment followed by ammonium sulfate leaching was also an effective method to recover REEs from the upgraded clayey waste material under mild conditions (<100 oC).
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    Valorization of hemicellulose hydrolyzates into eco-friendly surfactants
    Liu, Wei; Roman, Maren (American Chemical Society, 2018-03-18)