Open Access. Powered by Scholars. Published by Universities.®

Computer Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Electrical and Computer Engineering

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 3301 - 3330 of 7216

Full-Text Articles in Computer Engineering

Encapsulation Process Of Propolis Extract By Casein Micelle Improves Sunscreen Activity, Muhamad Sahlan, Dara Dienayati, Darul Hamdi, Soraya Zahra, Heri Hermansyah, Malyn Chulasiri Apr 2017

Encapsulation Process Of Propolis Extract By Casein Micelle Improves Sunscreen Activity, Muhamad Sahlan, Dara Dienayati, Darul Hamdi, Soraya Zahra, Heri Hermansyah, Malyn Chulasiri

Makara Journal of Technology

Propolis, a wax bee glue, have antioxidant activity and effective as broad spectrum UVB and UVA photoprotection sunscreens agent. To improve photoprotection activity in sunscreen cream, the propolis was encapsulated by casein micelle. The Indonesian propolis was extracted by ethanol and separated the wax by freeze precipitation. The extract was encapsulated by casein and reduced their size by ball mill homogenizer with the encapsulation efficiency about 80% and size of particles about 80 nm. The particles was applied in sunscreen cream, evaluate their stabillity and photoprotection activity Sun Protection Factor (SPF) spectrophotometer (Optometric 290s). The results shows that the selected …


Nano-Channels Early Formation Investigation On Stainless Steel 316ti After Immersion In Molten Pb-Bi, Abu Khalid Rivai, Mardiyanto Mardiyanto, Annette Heinzel Apr 2017

Nano-Channels Early Formation Investigation On Stainless Steel 316ti After Immersion In Molten Pb-Bi, Abu Khalid Rivai, Mardiyanto Mardiyanto, Annette Heinzel

Makara Journal of Technology

Development of fuel cladding and structural materials in Pb-Bi environment, especially at high temperature, is a critical issue for the deployment of LFR (Lead alloy-cooled Fast Reactor) and ADS (Accelerator Driven Transmutation System). This is because of the corrosive characteristic of Pb-Bi to metals as constituent materials of fuel cladding and structural of the reactors. Corrosion test of a high-chromium austenitic stainless steel i.e. SS316Ti in molten Pb-Bi at 550 ºC has been carried out for about 300 hours continuously. The characterization using SEM-EDS (Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy) showed that an iron oxide as the outer …


Synthesis Of Libob Fine Powder To Increase Solubility, Etty Marti Wigayati, Titik Lestariningsih, Christin Rina Ratri, Ibrahim Purawiardi, Bambang Prihandoko Apr 2017

Synthesis Of Libob Fine Powder To Increase Solubility, Etty Marti Wigayati, Titik Lestariningsih, Christin Rina Ratri, Ibrahim Purawiardi, Bambang Prihandoko

Makara Journal of Technology

Lithium bis (oxalate) borate or LiBOB compound has captured interest of researchers, because it is potentially viable to be used as electrolyte salt in lithium-ion battery system. This compound is easy to synthesize and considered to be more environmentally friendly compared to conventional electrolyte salt because LiBOB does not contain halogen element. This research focused on the synthesis of LiBOB fine powder, which main purpose is improving LiBOB salt solubility in liquid electrolyte solution. This will aid the ion transfer between electrodes which in turn will increase the electrolyte performance. Solid state reaction was employed in this experiment. Synthesis of …


Influence Of Polyethylene Glycol (Peg) In Cmc-Nh4br Based Polymer Electrolytes: Conductivity And Electrical Study, Nur Khalidah Zainuddin, Ahmad Salihin Samsudin Apr 2017

Influence Of Polyethylene Glycol (Peg) In Cmc-Nh4br Based Polymer Electrolytes: Conductivity And Electrical Study, Nur Khalidah Zainuddin, Ahmad Salihin Samsudin

Makara Journal of Technology

The present work was carried with new type and promising polymer electrolytes system by development of carboxyl methylcellulose (CMC) doped NH4Br and plasticized with polyethylene glycol (PEG). The sample was successfully prepared via solution casting with no separation phase and good mechanical properties. The electrical conductivity and thermal conductivity of CMC-NH4Br-PEG based PEs system have been measured by the electrical impedance spectroscopy method in the temperature range of 303–373 K. The highest ionic conductivity gained is 2.48 x 10-3 Scm-1 at ambient temperature for sample contain with 8 wt. % PEG. It can be concluded that the plasticized is accountable …


Purification Simulation With Vapor Permeation And Distillation-Adsorption In Bioethanol Plant, Misri Gozan, Mia Sari Setiawan, Kenny Lischer Apr 2017

Purification Simulation With Vapor Permeation And Distillation-Adsorption In Bioethanol Plant, Misri Gozan, Mia Sari Setiawan, Kenny Lischer

Makara Journal of Technology

High purity of Bioethanol is required in biofuel mixing with gasoline (EXX). In bioethanol production line, the azeotropic property of ethanol-water becomes the barrier for purification process. This study examined two bioethanol separation processes by support of simulation tools, Superpro Designer 9.0 software. Ethanol purity and a low costeconomical process were the major considerations. Purification method of vapor permeation membrane technology was compared with distillation-adsorption method. Data from previous lab experiments and some literatures were used. The results showed that distillation-adsorption method is more economical compared to vapor permeation technology. Payback period of the simulation is 3.9 years and 4.3 …


An Efficient And Cost Effective Fpga Based Implementation Of The Viola-Jones Face Detection Algorithm, Peter Irgens, Curtis Bader, Theresa Lé, Devansh Saxena, Cristinel Ababei Apr 2017

An Efficient And Cost Effective Fpga Based Implementation Of The Viola-Jones Face Detection Algorithm, Peter Irgens, Curtis Bader, Theresa Lé, Devansh Saxena, Cristinel Ababei

Electrical and Computer Engineering Faculty Research and Publications

We present an field programmable gate arrays (FPGA) based implementation of the popular Viola-Jones face detection algorithm, which is an essential building block in many applications such as video surveillance and tracking. Our implementation is a complete system level hardware design described in a hardware description language and validated on the affordable DE2-115 evaluation board. Our primary objective is to study the achievable performance with a low-end FPGA chip based implementation. In addition, we release to the public domain the entire project. We hope that this will enable other researchers to easily replicate and compare their results to ours and …


Physiologically-Aware Communication Architecture For Transmission Of Biomedical Signals In Basns For Emerging Iot Applications, Jose Santos, Dongming Peng, Hamid Sharif Apr 2017

Physiologically-Aware Communication Architecture For Transmission Of Biomedical Signals In Basns For Emerging Iot Applications, Jose Santos, Dongming Peng, Hamid Sharif

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

This research work proposes a novel physiologicallyaware communication architecture for the transmission of biomedical signals in BASNs (Body Area Sensor Networks) and wearables for emerging IoT applications. The architecture to fulfill the following objectives:

• Reduce volume of biomedical data in IoT networks and Internet infrastructure.

• Minimize the required computational load of biomedical data on the cloud side.

• Extend the lifetime of the mobile wearable/BASN through improved energy savings.

This architecture is generalizable to class of biomedical signals. It prevents large volume of biomedical data to be generated; uses patient state to control almost any system parameter; achieves …


Reducing Graphene–Metal Contact Resistance Via Laser Nano-Welding, Kamran Keramatnejad, H. Rabiee Golgir, Y. S. Zhou, D. W. Li, X. Huang, Yongfeng Lu Apr 2017

Reducing Graphene–Metal Contact Resistance Via Laser Nano-Welding, Kamran Keramatnejad, H. Rabiee Golgir, Y. S. Zhou, D. W. Li, X. Huang, Yongfeng Lu

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

The large graphene-metal contact resistance is a major limitation for development of graphene electronics. graphene behaves as an insulator for out-of-plane carrier transport to metallic contacts.

Laser nano-welding was developed and led to RC reductions of up to 84%.

Localized laser irradiation at the edges of graphene led to the formation of chemically active point defects.

Precise structural modifications and formation of G-M bonding led to improved carrier efficiency in graphene devices.


Special Issue Of Best Papers From The 11th International Conference On Systematic Approaches To Digital Forensic Engineering (Sadfe 2016) Mar 2017

Special Issue Of Best Papers From The 11th International Conference On Systematic Approaches To Digital Forensic Engineering (Sadfe 2016)

Journal of Digital Forensics, Security and Law

The SADFE series feature the different editions of the International Conference on Systematic Approaches to Digital Forensics Engineering. Now in its eleventh edition, SADFE has established itself as the premier conference for researchers and practitioners working in Systematic Approaches to Digital Forensics Engineering.

SADFE 2016, the eleventh international conference on Systematic Approaches to Digital Forensic Engineering was held in Kyoto, Japan, September 20 - 22, 2016.

Digital forensics engineering and the curation of digital collections in cultural institutions face pressing and overlapping challenges related to provenance, chain of custody, authenticity, integrity, and identity. The generation, analysis and sustainability of digital …


Compression Of Virtual-Machine Memory In Dynamic Malware Analysis, James E. Fowler Ph.D. Mar 2017

Compression Of Virtual-Machine Memory In Dynamic Malware Analysis, James E. Fowler Ph.D.

Journal of Digital Forensics, Security and Law

Lossless compression of memory dumps from virtual machines that run malware samples is considered with the goal of significantly reducing archival costs in dynamic-malware-analysis applications. Given that, in such dynamic-analysis scenarios, malware samples are typically run in virtual machines just long enough to activate any self-decryption or other detection- avoidance maneuvers, the virtual-machine memory typically changes little from that of the baseline state, with the difference being attributable in large degree to the loading of additional executables and libraries. Consequently, delta coding is proposed to compress the current virtual-machine memory dump by coding its differences with respect to a predicted …


Front Matter Mar 2017

Front Matter

Journal of Digital Forensics, Security and Law

No abstract provided.


Find Me If You Can: Mobile Gps Mapping Applications Forensic Analysis & Snavp The Open Source, Modular, Extensible Parser, Jason Moore, Ibrahim Baggili, Frank Breitinger Mar 2017

Find Me If You Can: Mobile Gps Mapping Applications Forensic Analysis & Snavp The Open Source, Modular, Extensible Parser, Jason Moore, Ibrahim Baggili, Frank Breitinger

Journal of Digital Forensics, Security and Law

The use of smartphones as navigation devices has become more prevalent. The ubiquity of hand-held navigation devices such as Garmins or Toms Toms has been falling whereas the ownership of smartphones and their adoption as GPS devices is growing. This work provides a comprehensive study of the most popular smartphone mapping applications, namely Google Maps, Apple Maps, Waze, MapQuest, Bing, and Scout, on both Android and iOS. It details what data was found, where it was found, and how it was acquired for each application. Based on the findings, the work allowed for the construction of a tool capable of …


A Forensic Email Analysis Tool Using Dynamic Visualization, Johannes Stadlinger, Andreas Dewald Mar 2017

A Forensic Email Analysis Tool Using Dynamic Visualization, Johannes Stadlinger, Andreas Dewald

Journal of Digital Forensics, Security and Law

Communication between people counts to the most important information of today’s business. As a result, in case of forensic investigations in big companies, analysis of communication data in general and especially email, as the still most widely used business communication platform with an immense and still growing volume, is a typical task in digital forensics. One of the challenges is to identify the relevant communication partners and structures in the suspects surrounding as quickly as possible in order to react appropriately and identify further targets of evaluation. Due to the amount of emails in typical inboxes, reading through all the …


Table Of Contents Mar 2017

Table Of Contents

Journal of Digital Forensics, Security and Law

No abstract provided.


Ip Flow Mobility In The Industry: From An Economic Perspective, Jun Huang, Fang Fang, Cong-Cong Xing, Yi Qian Mar 2017

Ip Flow Mobility In The Industry: From An Economic Perspective, Jun Huang, Fang Fang, Cong-Cong Xing, Yi Qian

Department of Electrical and Computer Engineering: Faculty Publications

The popularity of social media together with the advancement of mobile Internet applications enabling the uploading of data plays a dominant role in the entire Internet traffic. IP flow mobility (IFOM) is proposed as an effective means to enhance the system capacity by offloading data from the cellular network to WiFi or Femtocells or other complementary networks. Although IFOM has been extensively investigated during the past few years, most of these studies, however, are concerned with IFOM technical issues only; little work regarding the IFOM application has been done from the service providers’ perspective. Unlike previous research, in this paper, …


Autoprov: An Automated File Provenance Collection Tool, Ryan A. Good Mar 2017

Autoprov: An Automated File Provenance Collection Tool, Ryan A. Good

Theses and Dissertations

A file's provenance is a detailing of its origins and activities. There are tools available that are useful in maintaining the provenance of a file. Unfortunately for digital forensics, these tools require prior installation on the computer of interest while provenance generating events happen. The presented tool addresses this by reconstructing a file's provenance from several temporal artifacts. It identifies relevant temporal and user correlations between these artifacts, and presents them to the user. A variety of predefined use cases and real world data are tested against to demonstrate that this software allows examiners to draw useful conclusions about the …


Framework For Industrial Control System Honeypot Network Traffic Generation, Htein A. Lin Mar 2017

Framework For Industrial Control System Honeypot Network Traffic Generation, Htein A. Lin

Theses and Dissertations

Defending critical infrastructure assets is an important but extremely difficult and expensive task. Historically, decoys have been used very effectively to distract attackers and in some cases convince an attacker to reveal their attack strategy. Several researchers have proposed the use of honeypots to protect programmable logic controllers, specifically those used to support critical infrastructure. However, most of these honeypot designs are static systems that wait for a would-be attacker. To be effective, honeypot decoys need to be as realistic as possible. This paper introduces a proof-of-concept honeypot network traffic generator that mimics genuine control systems. Experiments are conducted using …


A Framework For Categorization Of Industrial Control System Cyber Training Environments, Evan G. Plumley Mar 2017

A Framework For Categorization Of Industrial Control System Cyber Training Environments, Evan G. Plumley

Theses and Dissertations

First responders and professionals in hazardous occupations undergo training and evaluations for the purpose of mitigating risk and damage. For example, helicopter pilots train with multiple categorized simulations that increase in complexity before flying a real aircraft. However in the industrial control cyber incident response domain, where incident response professionals help detect, respond and recover from cyber incidents, no official categorization of training environments exist. To address this gap, this thesis provides a categorization of industrial control training environments based on realism. Four levels of environments are proposed and mapped to Blooms Taxonomy. This categorization will help organizations determine which …


Applying Cyber Threat Intelligence To Industrial Control Systems, Matthew P. Sibiga Mar 2017

Applying Cyber Threat Intelligence To Industrial Control Systems, Matthew P. Sibiga

Theses and Dissertations

A cybersecurity initiative known as cyber threat intelligence (CTI) has recently been developed and deployed. The overall goal of this new technology is to help protect network infrastructures. Threat intelligence platforms (TIPs) have also been created to help facilitate CTI effectiveness within organizations. There are many benefits that both can achieve within the information technology (IT) sector. The industrial control system (ICS) sector can also benefit from these technologies as most ICS networks are connected to IT networks. CTI and TIPs become resourceful when using indicators of compromise (IOCs) from known ICS malware attacks and an open source intrusion detection …


Special Section On Electrical Contacts, Ronald A. Coutu Jr., Ravi Mahajan Mar 2017

Special Section On Electrical Contacts, Ronald A. Coutu Jr., Ravi Mahajan

Electrical and Computer Engineering Faculty Research and Publications

Welcome to the Special Topics Section dedicated to the 2015 Holm Conference on Electrical Contacts. This Special Section contains six high-quality papers that comprehensively describe the state of the art and potential future directions for topics of great interest to our readers. The Editor-in-Chief (EIC), in consultation with the other EICs, Associate Editors (AEs), and domain experts, selects the topics for the Special Sections, and a Guest Editor or AE (GE/AE) who is a leading expert in the technical area then directs the solicitation and peer review of the papers. In cases where the GE/AE is also an author, the …


Thz Metamaterial Characterization Using Thz-Tds, Christopher H. Kodama, Ronald A. Coutu Jr. Mar 2017

Thz Metamaterial Characterization Using Thz-Tds, Christopher H. Kodama, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

The purpose of this chapter is to familiarize the reader with metamaterials and describe terahertz (THz) spectroscopy within metamaterials research. The introduction provides key background information on metamaterials, describes their history and their unique properties. These properties include negative refraction, backwards phase propagation, and the reversed Doppler Effect. The history and theory of metamaterials are discussed, starting with Veselago’s negative index materials work and Pendry’s publications on physical realization of metamaterials. The next sections cover measurement and analyses of THz metamaterials. THz Time-domain spectroscopy (THz-TDS) will be the key measurement tool used to describe the THz metamaterial measurement process. Sample …


Image-Based Multi-Target Tracking Through Multi-Bernoulli Filtering With Interactive Likelihoods, Anthony B. Hoak, Henry P. Medeiros, Richard J. Povinelli Mar 2017

Image-Based Multi-Target Tracking Through Multi-Bernoulli Filtering With Interactive Likelihoods, Anthony B. Hoak, Henry P. Medeiros, Richard J. Povinelli

Electrical and Computer Engineering Faculty Research and Publications

We develop an interactive likelihood (ILH) for sequential Monte Carlo (SMC) methods for image-based multiple target tracking applications. The purpose of the ILH is to improve tracking accuracy by reducing the need for data association. In addition, we integrate a recently developed deep neural network for pedestrian detection along with the ILH with a multi-Bernoulli filter. We evaluate the performance of the multi-Bernoulli filter with the ILH and the pedestrian detector in a number of publicly available datasets (2003 PETS INMOVE, Australian Rules Football League (AFL) and TUD-Stadtmitte) using standard, well-known multi-target tracking metrics (optimal sub-pattern assignment (OSPA) and classification …


On The Development Of A One-Time Pad Generator For Personalising Cloud Security, Paul Tobin, Lee Tobin, Michael Mckeever, Jonathan Blackledge Feb 2017

On The Development Of A One-Time Pad Generator For Personalising Cloud Security, Paul Tobin, Lee Tobin, Michael Mckeever, Jonathan Blackledge

Conference papers

Cloud computing security issues are being reported in newspapers, television, and on the Internet, on a daily basis. Furthermore, in 2013, Edward Snowden alleged backdoors were placed in a number of encryption systems by the National Security Agency causing confidence in public encryption to drop even further. Our solution allows the end-user to add a layer of unbreakable security by encrypting the data locally with a random number generator prior to uploading data to the Cloud. The prototype one-time pad generator is impervious to cryptanalysis because it generates unbreakable random binary sequences from chaos sources initiated from a natural noise. …


Women In It: Be The Change, Marcia L. Dority Baker Feb 2017

Women In It: Be The Change, Marcia L. Dority Baker

Information Technology Services: Publications

The influence of established women in IT — specifically Florence Hudson and Melissa Woo — encouraged a librarian to apply for a position in Information Technology Services at the University of Nebraska–Lincoln.

A hands-on approach to planning the IT Leadership conference developed a strong collaborative network that also helped grow attendance.

Paying attention to the pros and cons of the 2016 conference guided the planners in modifying their approach to the upcoming October 2017 conference and its focus on diversity and inclusion.

A main goal for future IT Leadership conferences focusing on women and diversity in IT is providing attendees …


A Fault-Tolerant T-Type Multilevel Inverter Topology With Increased Overload Capability And Soft-Switching Characteristics, Jiangbiao He, Ramin Katebi, Nathan Weise, Nabeel Demerdash, Lixiang Wei Feb 2017

A Fault-Tolerant T-Type Multilevel Inverter Topology With Increased Overload Capability And Soft-Switching Characteristics, Jiangbiao He, Ramin Katebi, Nathan Weise, Nabeel Demerdash, Lixiang Wei

Electrical and Computer Engineering Faculty Research and Publications

he performance of a novel three-phase four-leg fault-tolerant T-type inverter topology is introduced in this paper. This inverter topology provides a fault-tolerant solution to any open-circuit and certain short-circuit switching faults in the power devices. During any of the fault-tolerant operation modes for these device faults, there is no derating required in the inverter output voltage or output power. In addition, overload capability is increased in this new T-type inverter compared to that in the conventional three-level T-type inverter. Such increase in inverter overload capability is due to the utilization of the redundant leg for overload current sharing with other …


Optimized Trajectory Generation For Car-Like Robots On A Closed Loop Track, Tyler Friedl Jan 2017

Optimized Trajectory Generation For Car-Like Robots On A Closed Loop Track, Tyler Friedl

Electronic Theses and Dissertations

This thesis presents a method for generating an optimized path through a given track. The path is generated by choosing waypoints throughout the track then iteratively optimizing the position of these waypoints. The waypoints are then connected by optimized paths represented by curvature polynomials. The end result is a path through the track represented as a spline of curvature polynomials. This method is applied to multiple simulated tracks and the results are presented. By generating and representing the paths in the continuous domain, the method has improved computational efficiency from many of the discrete methods used to generate an optimal …


Automatic Power Management For Instructional Computers At Humboldt State University: A Calculation Of Potential Energy Savings And Greenhouse Gas Emissions Reductions, Nicholas F. Flenghi Jan 2017

Automatic Power Management For Instructional Computers At Humboldt State University: A Calculation Of Potential Energy Savings And Greenhouse Gas Emissions Reductions, Nicholas F. Flenghi

Projects

Computers consume an estimated 5,610 GWh per year in California alone. Much of that energy is consumed by computers that are not being used. In this project, detailed user login data are used to estimate the energy consumption of instructional computers at Humboldt State University (HSU) over the course of one semester. The data are also used to estimate the potential energy savings from automating the shutdown process. Potential cost savings and greenhouse gas (GHG) emissions reductions resulting from implementing an automatic-shutdown power management plan are also calculated.

There are approximately 1,000 computers used for teaching and learning purposes at …


Drop (Drone Open Source Parser) Your Drone: Forensic Analysis Of The Dji Phantom Iii, Devon R. Clark, Christopher S. Meffert, Ibrahim Baggili, Frank Breitinger Jan 2017

Drop (Drone Open Source Parser) Your Drone: Forensic Analysis Of The Dji Phantom Iii, Devon R. Clark, Christopher S. Meffert, Ibrahim Baggili, Frank Breitinger

Electrical & Computer Engineering and Computer Science Faculty Publications

The DJI Phantom III drone has already been used for malicious activities (to drop bombs, remote surveillance and plane watching) in 2016 and 2017. At the time of writing, DJI was the drone manufacturer with the largest market share. Our work presents the primary thorough forensic analysis of the DJI Phantom III drone, and the primary account for proprietary file structures stored by the examined drone. It also presents the forensically sound open source tool DRone Open source Parser (DROP) that parses proprietary DAT files extracted from the drone's nonvolatile internal storage. These DAT files are encrypted and encoded. The …


An Ensemble Learning Framework For Anomaly Detection In Building Energy Consumption, Daniel B. Araya, Katarina Grolinger, Hany F. Elyamany, Miriam Am Capretz, Girma T. Bitsuamlak Jan 2017

An Ensemble Learning Framework For Anomaly Detection In Building Energy Consumption, Daniel B. Araya, Katarina Grolinger, Hany F. Elyamany, Miriam Am Capretz, Girma T. Bitsuamlak

Electrical and Computer Engineering Publications

During building operation, a significant amount of energy is wasted due to equipment and human-related faults. To reduce waste, today's smart buildings monitor energy usage with the aim of identifying abnormal consumption behaviour and notifying the building manager to implement appropriate energy-saving procedures. To this end, this research proposes a new pattern-based anomaly classifier, the collective contextual anomaly detection using sliding window (CCAD-SW) framework. The CCAD-SW framework identifies anomalous consumption patterns using overlapping sliding windows. To enhance the anomaly detection capacity of the CCAD-SW, this research also proposes the ensemble anomaly detection (EAD) framework. The EAD is a generic framework …


Qos Recommendation In Cloud Services, Xianrong Zheng, Li Da Xu, Sheng Chai Jan 2017

Qos Recommendation In Cloud Services, Xianrong Zheng, Li Da Xu, Sheng Chai

Information Technology & Decision Sciences Faculty Publications

As cloud computing becomes increasingly popular, cloud providers compete to offer the same or similar services over the Internet. Quality of service (QoS), which describes how well a service is performed, is an important differentiator among functionally equivalent services. It can help a firm to satisfy and win its customers. As a result, how to assist cloud providers to promote their services and cloud consumers to identify services that meet their QoS requirements becomes an important problem. In this paper, we argue for QoS-based cloud service recommendation, and propose a collaborative filtering approach using the Spearman coefficient to recommend cloud …