Tuwhera Research Repository

The Tuwhera Research Repository provides sustainable open access and archiving to a broad range of AUT produced research - theses, research outputs and datasets.

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Access status: Open Access ,
Wi-Fi 7 Streaming Stability: A Multi-Band, Multi-Bitrate Performance Assessment
(MDPI AG, 2026-10-14) Sarkar, Nurul I; Gul, Sonia
Wi-Fi 7 (IEEE 802.11be) introduces key physical and medium access control (MAC) layer advancements, including wider channel bandwidths up to 320 MHz, 4096-QAM modulation, preamble puncturing, and tri-band operation across 2.4 GHz, 5 GHz, and 6 GHz to support high-bandwidth and low-latency wireless applications. Despite these advances, the application-level streaming behavior of Wi-Fi 7 networks under realistic multi-factor conditions remains insufficiently characterized in the literature. This paper presents an empirical and simulation-based evaluation of Wi-Fi 7 streaming stability, assessing, with one variable changed at a time, the separate effects of received signal strength (RSS), codec bitrate, frequency band, network layer protocol, media type, and network contention on playback delay for MP3 audio and MP4 video streams. A physical testbed comprising a Wi-Fi 7 access point and client devices is used to conduct controlled experiments across varying signal and network conditions, complemented by OMNeT++ simulation to assess MAC layer scalability under higher client densities. Each band was evaluated independently with Multi-Link Operation (MLO) disabled, so the results characterize single-link operation on Wi-Fi 7 hardware rather than coordinated 802.11be MLO; the codec bitrates tested (192–320 kbps) are low relative to the link capacity, so link saturation was not exercised in the testbed. Results show that RSS degradation non-linearly increases playback delay in the pooled results. Pooled across the conditions tested, not as a strong-signal subset, the bands rank as follows by mean playback delay: 2.4 GHz (7.05 s), 5 GHz (5.21 s), and 6 GHz (4.26 s). Higher codec bitrates were associated with lower playback delay, most plausibly because VLC’s pre-buffering threshold is filled sooner at higher bitrates on an unsaturated link. Network layer protocol (IPv4 vs. IPv6) showed no material difference in mean playback delay. Network contention, modeled through increasing concurrent client counts, increased playback delay from one to three testbed clients, and simulated network-layer delay increased from 40 to 80 clients. These findings provide a descriptive, multi-parameter, single-link performance baseline for Wi-Fi 7 audio and video streaming, providing practical guidance for network deployment and serving as a reference for future benchmarking of next-generation Wi-Fi 8 (IEEE 802.11bn) networks.
Access status: Open Access ,
Mapping the Invisible: Integrating Nighttime Light and Social Sensing to Explore Hidden Cross-Border Economies
(MDPI AG, 2026-10-15) Zhai, Xiaofang; Zhang, Fan; Xiao, Zhifeng; Xu, Haoyang; Yan, Wei Qi
Against the backdrop of the continuing spread of cross-border telecommunications fraud and the scarcity of conventional data, this study examines how publicly accessible multi-source data can be used to monitor and characterize the spatiotemporal evolution of known or suspected fraud compounds under data-scarce conditions. Focusing on eight representative and manually delineated fraud compounds in Myanmar’s border regions, it develops a three-dimensional “space–time–representation” framework that integrates 2017–2025 VIIRS nighttime lights (NTL), Sentinel-1/2-derived built-up area (BUA) expansion, and Baidu Index time series as a proxy for Chinese-language public attention. Dynamic time warping (DTW) is used to examine temporal alignment between NTL dynamics and public attention, while spatial autocorrelation and exploratory grouping based on DTW dissimilarity are applied to characterize spatial clustering and heterogeneous temporal patterns. The results show that BUA expansion and nighttime brightness are not uniformly coupled across compounds and years. After excluding partial-year 2025 observations, the complete-year 2017–2024 park–year analysis indicates weak aggregate associations between BUA and annual mean NTL, highlighting the need to interpret the two indicators as complementary but non-equivalent proxies. NTL changes do not necessarily evolve synchronously with changes in public attention, suggesting potential value for monitoring and prioritization rather than direct early-warning or verification of illicit activities. The global Moran’s I of 0.2476 indicates significant spatial clustering of nighttime-light values within the defined compound–buffer analysis units. DTW alignment reveals stronger consistency between nighttime lights and Baidu Index attention in the Daxiang and Dingsheng compounds, whereas KK Park and Yatai City show weaker public-search responses relative to observed NTL dynamics. Exploratory grouping identifies three patterns of NTL–public attention correspondence, highlighting heterogeneous relationships between observed nighttime-light dynamics and external information visibility. The study demonstrates the complementarity of remote sensing and social sensing data under data scarcity and proposes a replicable approach for remote monitoring, typological characterization, and evidence-informed governance prioritization of known or suspected fraud compounds. The proposed approach should be interpreted as a screening and analytical framework that provides directional evidence rather than as direct verification of illicit activity or compound-specific operational status.
Access status: Open Access ,
Effects of Differing Levels of Carbohydrate Restriction on Mood Achievement of Nutritional Ketosis, and Symptoms of Carbohydrate Withdrawal in Healthy Adults: A Randomized Clinical Trial
(Elsevier BV, 2019-11-23) Harvey, Cliff; Schofield, Grant; Zinn, Caryn; Thornley, Simon
Objectives: To our knowledge, minimal research exists on the effects of diets differing in carbohydrate restriction on symptoms of carbohydrate withdrawal and mood, and the achievement of nutritional ketosis (NK). The aim of this study was to compare ketonaemia, symptoms of carbohydrate withdrawal, and mood. We hypothesized that a moderate carbohydrate restriction would result in fewer symptoms and a reduced effect on mood. Methods: Seventy-seven healthy participants (25 men and 52 women; mean age: 39 y, range: 25–49; mean body mass index 27 kg/m2, range: 20–39) were randomized to receive either a very-low-carbohydrate ketogenic diet (VLCKD), low-carbohydrate diet (LCD), or moderately low-carbohydrate diet (MCD), containing 5%, 15%, and 25% total energy (TE) from carbohydrate, respectively, for 3 wk. Fasting blood ketone measures were recorded daily upon waking along with a data from symptom questionnaire and a 5-point mood-state scale. Using analysis of variance and a 5% two-sided α level to determine statistical significance, between-group outcomes were analyzed. Additional association and analyses were conducted by multiple linear regression. Results: In 75 of 77 initial participants included for analysis, mean serum levels of β-hydroxybutyrate (βOHB) were increased by 0.27 ± 0.32, 0.41 ± 0.38, and 0.62 ± 0.49 mmol/L for MCD, LCD, and VLCKD, respectively (P = 0.013). The achievement of NK was consistent for both VLCKD and LCD groups and sporadic for the MCD group. Only the VLCKD group exhibited 95% confidence interval levels that were consistently ≥0.5 mmol/L. The overall mean change in sum of symptoms scores (SOSS) from baseline was 0.81 ± 2.84 (P < 0.001). Changes in SOSS were highest in the VLCKD group (1.49 ± 2.47), followed by LCD (0.65 ± 2.70) and MCD (0.18 ± 3.3; P = 0.264). Small, statistically significant increases were seen for headache severity, constipation, diarrhea, halitosis, muscle cramps and muscle weakness, and light-headedness, whereas intestinal bloating and craving for sugar and starch improved from baseline. Only halitosis (P = 0.039) and muscle weakness (P = 0.005) differed significantly between the groups. Mood improved significantly from baseline overall, but there was no significant difference between groups (P = 0.181) Conclusions: Diets containing 5% TE from carbohydrates are ketogenic, but diets containing between 15% and 25% TE from carbohydrates can also result in mean βOHB ≥0.5 mmol/L. There was no meaningful difference in symptoms of carbohydrate withdrawal between diets that contain 5% to 25% TE from carbohydrate, and mood was improved overall, with no significant difference between interventions. Our conclusion, therefore, is that reduced carbohydrate diets should be prescribed by need rather than the desire to mitigate symptoms of carbohydrate withdrawal.
Access status: Open Access ,
An Optimisation Process to Motivate Effective Adoption of BIM for Refurbishment of Complex Buildings in New Zealand
(Elsevier, 2019-06-23) Okakpu, Anthony; GhaffarianHoseini, Ali; Tookey, John; Haar, Jarrod; GhaffarianHoseini, Amirhosein
Despite the multidisciplinary networks involved in refurbishment of complex building projects, the lack of BIM adoption signifies lack of real BIM benefits towards acceptance of BIM within Architecture, Engineering and Construction (AEC). To this end, this study empirically examines the potential real benefits between traditional network and BIM network for a real-time refurbishment case study project, through agent-based simulation modelling. A social network analysis theory is adapted to model the project interaction networks and a BIM prototype network. An assessment of the main stakeholders for BIM perception is carried out. We offered three prototype interaction networks for comparison of real BIM benefit. An agent-based Bayesian network model is used to simulate the propagation of design error within the project networks. The result of the analysis show that BIM project diffuses error efficiently, while stakeholders recovers faster and nearly at the same time than traditional network. The optimised network shows better performance to the traditional network, when there is early involvement of subcontractors. The main contribution of this study is providing a novel approach to compare real benefits for traditional method to BIM method for refurbishment project and to provide avenue for project stakeholders to optimise their interaction through adoption of BIM.
Access status: Open Access ,
Depression Prevalence in Postgraduate Students and Its Association With Gait Abnormality
(Institute of Electrical and Electronics Engineers (IEEE), 2019-12-16) Fang, Jing; Wang, Tao; Li, Cancheng; Hu, Xiping; Ngai, Edith; Seet, Boon-Chong; Cheng, Jun; Guo, Yi; Jiang, Xin
In recent years, an increasing number of university students are found to be at high risk of depression. Through a large scale depression screening, this paper finds that around 6.5% of the university postgraduate students in China experience depression. We then investigate whether the gait patterns of these individuals have already changed as depression is suggested to associate with gait abnormality. Significant differences are found in several spatiotemporal, kinematic and postural gait parameters such as walking speed, stride length, head movement, vertical head posture, arm swing, and body sway, between the depressed and non-depressed groups. Applying these features to classifiers with different machine learning algorithms, we examine whether natural gait analysis may serve as a convenient and objective tool to assist in depression recognition. The results show that when using a random forest classifier, the two groups can be classified automatically with a maximum accuracy of 91.58%. Furthermore, a reasonable accuracy can already be achieved by using parameters from the upper body alone, indicating that upper body postures and movements can effectively contribute to depression analysis.