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11 pages, 1043 KiB

Open AccessArticle

Mining Product Reviews for Important Product Features of Refurbished iPhones

by Atefeh Anisi, Gül E. Okudan Kremer and Sigurdur Olafsson

Information 2025, 16(4), 276; https://doi.org/10.3390/info16040276 - 29 Mar 2025

Viewed by 437

Problem: Remanufacturers want to increase consumer interest in refurbished products, which motivates the need to understand which product features are important to buyers of refurbished products such as mobile phones. Research Questions: This study addresses two questions. First, which product features are most important for buyers of refurbished iPhones? Second, how do those preferences differ from the preferences of buyers of new iPhones? Methods: Online reviews of iPhones are obtained and converted into a document–term matrix. Using this text model, three subsets of features are identified using statistical analysis of frequency of mention: most frequent, average, and least frequent. A logistic regression (LR) model is then used to identify which features are most predictive of whether a review is for a new or refurbished phone. Results: Buyers of refurbished phones mention battery health, screen/display, shell condition, and brand significantly more often than other features. Directly contrasting reviews of refurbished versus new phones shows that shell condition, brand, speaker, and charger are found to be the most predictive product features indicated in reviews for refurbished phones. Of those, the shell condition is significantly more predictive than the others. Implications: The results identify product features that remanufacturers of iPhones can emphasize to increase customer demand. Full article

(This article belongs to the Special Issue Big Data Analytics, Decision-Making Models, and Their Applications)

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14 pages, 3561 KiB

Open AccessArticle

Safety Assessment and Uncertainty Quantification of Electromagnetic Radiation from Mobile Phones to the Human Head

by Miao Yi, Boqi Wu, Yang Zhao, Tianbo Su and Yaodan Chi

Appl. Sci. 2023, 13(14), 8107; https://doi.org/10.3390/app13148107 - 12 Jul 2023

Cited by 1 | Viewed by 1941

Abstract

With the rapid development of the mobile communication technology, the design of mobile phones has become more complex, and research on the electromagnetic radiation from mobile phones that reaches the human head has become important. Therefore, first of all, a model of mobile phone daily use was established. Then, based on the established simulation model, the safety of human head exposure to mobile phones was evaluated. The generalized polynomial chaos (gPC) method was used to establish a proxy model of the specific absorption rate (SAR) of the human head at different frequencies to perform a parameter uncertainty quantification (UQ). Finally, the Sobol method was used to quantify the influence of relevant variables on the SAR. The simulation results showed that the gPC method can save time and cost while ensuring accuracy, and the SAR value is greatly influenced by the electromagnetic materials of the mobile phone shell. Combined with the above analysis, this paper can provide reasonable suggestions for the design of mobile phone electromagnetic materials. Full article

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8 pages, 2670 KiB

Open AccessArticle

Preparation and Characterization of High-Strength Glass-Ceramics via Ion-Exchange Method

by Jianwei Lu, Haifeng Wang, Juanjuan Zhu, Qiuju Zheng, Linfeng Ding and Weizhong Jiang

Materials 2021, 14(19), 5477; https://doi.org/10.3390/ma14195477 - 22 Sep 2021

Cited by 6 | Viewed by 2584

Abstract

Lithium aluminosilicate glass-ceramics (LAS GCs) are ideal shell materials for mobile phones; however, the mechanical properties of LAS GCs are comparatively lower than that of other shell materials. In this work, the impact of TiO₂/(TiO₂ + ZrO₂) ratio on properties of LAS GCs was studied and the ion-exchange methods were applied to improve the mechanical properties of LAS GCs. The results show that LAS GCs with TiO₂/(TiO₂ + ZrO₂) = 1/2 exhibit the best flexural strength (109 MPa) and Vickers hardness (525 Kg/mm²). The as-prepared glass was nucleated at 560 °C for 1 h and crystallized at 720 °C for 0.5 h. The main crystalline phases of LAS GCs are β-quartz solid solution, β-spodumene solid solution, and Li₂SiO₃. Moreover, the flexural strength and Vickers hardness of LAS GCs with TiO₂/(TiO₂ + ZrO₂) = 1/2 further increased to 356 MPa and 838 Kg/mm² after an ion-exchange at 420 °C for 6 h in pure KNO₃ molten salt. The LAS GCs with enhanced mechanical strength have the potential to be applied as mobile phone back panels. Full article

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17 pages, 5401 KiB

Open AccessArticle

Numerical Simulation and Experimental Analysis of the Semi-Solid Thixotropic Extrusion Forming Process for Producing the Thin-Wall Wrought Aluminum Alloy Mobile Phone Shells

by Yi Guo, Yongfei Wang and Shengdun Zhao

Materials 2021, 14(13), 3505; https://doi.org/10.3390/ma14133505 - 23 Jun 2021

Cited by 6 | Viewed by 2168

Abstract

Aluminum alloys have been widely used in various engineering applications due to their excellent physical properties such as low density, high strength and good cutting capacity. In this paper, the semi-solid thixotropic extrusion forming process is proposed to produce aluminum alloy 6063 shells for mobile phones. The effects of the operating parameters on the equivalent stress distribution, velocity field, temperature field, and the load of the top mould were investigated through numerical simulations. Optimal parameters were identified from the simulation results. The experiment was then conducted at these optimal parameters. The macromorphology and microstructure results of the mobile phone shells produced from the experiment are presented and discussed. It was found that the optimal process parameters for preparing aluminum alloy 6063 shell by the semi-solid thixotropic extrusion process were a billet temperature of 630 °C, mould temperature of 400 °C, and top mould speed of 10 mm/s. It was found that the mobile phone shells fabricated under the optimal operating conditions were fully filled with a clear outline and a smooth surface. The solid grains in the microstructure were small, uniform and nearly spherical. The average grain size of the microstructure for the product was obtained as 76.92 μm and the average shape factor was found as 0.76. Full article

(This article belongs to the Special Issue Recent Advances and Trends in Metal Forming)

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23 pages, 1280 KiB

Open AccessArticle

Optimized Authentication System with High Security and Privacy

by Uttam Sharma, Pradeep Tomar, Syed Sadaf Ali, Neetesh Saxena and Robin Singh Bhadoria

Electronics 2021, 10(4), 458; https://doi.org/10.3390/electronics10040458 - 13 Feb 2021

Cited by 14 | Viewed by 3608

Abstract

Authentication and privacy play an important role in the present electronic world. Biometrics and especially fingerprint-based authentication are extremely useful for unlocking doors, mobile phones, etc. Fingerprint biometrics usually store the attributes of the minutia point of a fingerprint directly in the database as a user template. Existing research works have shown that from such insecure user templates, original fingerprints can be constructed. If the database gets compromised, the attacker may construct the fingerprint of a user, which is a serious security and privacy issue. Security of original fingerprints is therefore extremely important. Ali et al. have designed a system for secure fingerprint biometrics; however, their technique has various limitations and is not optimized. In this paper, first we have proposed a secure technique which is highly robust, optimized, and fast. Secondly, unlike most of the fingerprint biometrics apart from the minutiae point location and orientation, we have used the quality of minutiae points as well to construct an optimized template. Third, the template constructed is in 3D shell shape. We have rigorously evaluated the technique on nine different fingerprint databases. The obtained results from the experiments are highly promising and show the effectiveness of the technique. Full article

(This article belongs to the Special Issue Cybersecurity for Wireless Networking)

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19 pages, 49666 KiB

Open AccessArticle

A Robotic Automatic Assembly System Based on Vision

by Rui Song, Fengming Li, Tianyu Fu and Jie Zhao

Appl. Sci. 2020, 10(3), 1157; https://doi.org/10.3390/app10031157 - 8 Feb 2020

Cited by 35 | Viewed by 12293

Abstract

At present, the production lines of mobile phones are mainly manual and semi-automatic. Robots are the most important tools used to improve the intelligence level of industry production. The design of an intelligent robotic assembly system is presented in this paper, which takes the assembly of screen components and shell components as examples. There are major factors restricting the application of robots, such as the calibration of diversified objects, the moving workpiece with incomplete information, and diverse assembly types. A method was proposed to solve these technological difficulties. The multi-module calibration method is used to transform the pose relationship between the robot, the conveyor belt, and the two cameras in the robot assembly system. Aiming at a workpiece moving with incomplete information, the minimum matrix method is proposed to detect the position. Then dynamic fetching is realized based on pose estimation of the moving workpiece. At last, the template matching method is used to identify the assembly area of the workpiece type. The proposed method was verified on a real platform with a LINKHOU LR4-R5 60 robot. Results showed that the assembly success rate was above 98%, and the intelligent assembly system of the robot can realize the assembly of mobile phone screens and back shells without any staff. Full article

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