title: A multidimensional activity theory framework for human computer interaction with Digital Twins

authors: Adeel, Aleeza

subjects: Digital Twins

abstract: This paper introduces a human-centred framework to address the interaction and usability challenges of complex Digital Twin (DT) systems by proposing a new generation of Activity Theory, named Pyramidal Activity Theory (PAT). Digital twins are virtual representations of physical processes, systems, or components that are continuously synchronised with real-world data. Despite their growing adoption across industries, their graphical representation remains challenging due to the diversity of application domains, where multiple models—spanning different users, phases, and scales—are typically distributed across heterogeneous software packages. These complexities often result in inconsistencies, fragmented workflows, and communication barriers across domains. The proposed model builds upon the previous generation of activity theory, extending it into a 3D pyramidal structure while excluding motivational factors to focus exclusively on interaction mechanics. PAT provides a coherent model for designing unified, user-centred interfaces by capturing dynamic interactions among the key elements of DT systems—Users, Tools (Models), Live Data, Interfaces, and Outcomes—and their interrelationships. Two case studies are presented to demonstrate its applicability. Case Study 1 maps human–system interactions in advanced manufacturing, clarifying roles and activity flows to make the framework understandable and directly applicable for practitioners. Case Study 2 validates PAT through an implemented prototype for industrial energy optimisation.

The proposed model introduces a novel 3D interaction paradigm, providing a scalable and adaptable framework for digital twin interface design. It improves usability, standardisation, and decision-making by clarifying stakeholder roles, reducing cognitive load through “black-box” model integration, and ensuring consistent logic from regional planning to unit-level control. The paper concludes with future research directions, including usability testing, interface refinement, and alignment with interoperability and accessibility standards.

text: A multidimensional activity theory framework for human computer interaction with Digital Twins This paper introduces a human-centred framework to address the interaction and usability challenges of complex Digital Twin (DT) systems by proposing a new generation of Activity Theory, named Pyramidal Activity Theory (PAT). Digital twins are virtual representations of physical processes, systems, or components that are continuously synchronised with real-world data. Despite their growing adoption across industries, their graphical representation remains challenging due to the diversity of application domains, where multiple models—spanning different users, phases, and scales—are typically distributed across heterogeneous software packages. These complexities often result in inconsistencies, fragmented workflows, and communication barriers across domains. The proposed model builds upon the previous generation of activity theory, extending it into a 3D pyramidal structure while excluding motivational factors to focus exclusively on interaction mechanics. PAT provides a coherent model for designing unified, user-centred interfaces by capturing dynamic interactions among the key elements of DT systems—Users, Tools (Models), Live Data, Interfaces, and Outcomes—and their interrelationships. Two case studies are presented to demonstrate its applicability. Case Study 1 maps human–system interactions in advanced manufacturing, clarifying roles and activity flows to make the framework understandable and directly applicable for practitioners. Case Study 2 validates PAT through an implemented prototype for industrial energy optimisation.

The proposed model introduces a novel 3D interaction paradigm, providing a scalable and adaptable framework for digital twin interface design. It improves usability, standardisation, and decision-making by clarifying stakeholder roles, reducing cognitive load through “black-box” model integration, and ensuring consistent logic from regional planning to unit-level control. The paper concludes with future research directions, including usability testing, interface refinement, and alignment with interoperability and accessibility standards.

year: 2025

title: Development of Bloodmeal Protein Thermoplastic Blends

authors: Marsilla, K. I. Ku

abstract: This study investigated the compatibilization of Novatein® Thermoplastic Protein (NTP) blends with other polymers. NTP was blended with three different types of polymers;a petroleum-based polyolefin, (low-linear density polyethylene, LLDPE); a biodegradable synthetic polyester, (polybutylene succinate, PBS) and a bioderived, compostable polyester, (poly (lactic acid), PLA). It was a relatively straightforward process to produce a compatible blend of LLDPE and NTP using a compatibilizer, regardless of the obvious difference in chemical structure between these polymers. Blending NTP with PBS, on the other hand, was much more challenging. It required two compatibilizers, added at different stages of blending to produce a compatible blend. For blends with PLA, a novel copolymer, itaconic anhydride grafted PLA (PLA-g-IA) was produced to be used as a compatibilizer and initial results suggested that PLA-g-IA may be a successful approach. 
Two different methods of compatibilization pathways were explored: the addition of a graft copolymer based on one of the components (in the case of NTP/LLDPE blends) or using compatibilizers that are not chemically the same as either component (in the case of NTP/PBS blends). Polyethylene grafted maleic anhydride (PE-g-MAH) was added to NTP/LLDPE blends and produced a blend with synergistic mechanical properties (the elongation at break exceeded the raw LLDPE properties). The water resistance of NTP was improved after blending with LLDPE, but it may compromise the compostability of the material. For NTP/PBS blends, two compatibilizers with different functional end-groups were used; these were (poly-2-ethyl-2-oxazoline)(PEOX) and (polymeric diphenyl diisocyanate)(pMDI). Using either of the compatibilizers individually in blends containing 50 % NTP resulted in poor mechanical properties. Compatibilization was accomplished with the addition of both two compatibilizers at different stages of blend preparation; PEOX dissolved in water and added during NTP production, while pMDI was added during injection moulding. This approach led to a tensile strength greater than that of pure PBS (24 MPa compared to 22 MPa). Dissolving PEOX in water improved the dispersion of the NTP phase throughout the PBS matrix via hydrogen bonding between water, PEOX and NTP. The addition of pMDI during injection moulding stabilized and strengthened the interactions between PBS and NTP, thereby leading to a superior blend.  
The compatibility between NTP and LLDPE or NTP and PBS were characterized using thermal and morphological properties as well as water resistance. Two Tgs were obtained for all blends, however, the addition of compatibilizers improved the adhesion between phases, evident from broader and lower height of Tg peaks. The morphology provided evidence of a homogenous dispersion of NTP in LLDPE. In NTP/PBS blends, the fracture mechanism changed from brittle to ductile with the addition of PEOX. Both NTP/LLDPE and NTP/PBS blends showed a phase inversion from a particle- dispersed morphology to a co-continuous morphology at compositions greater than 50% NTP. The water resistance also improved with the addition of LLDPE and PBS.   
Reactive extrusion was used to produce a copolymer, itaconic anhydride grafted poly (lactic acid) (PLA-g-IA). Different initiator (dicumyl peroxide) and monomer (IA) concentrations were used to optimize the degree of grafting. 0.75% was the highest degree of grafting and showed minimal chain scission evident from the polymer’s intrinsic viscosity. The reaction kinetics of grafting and the effect of grafting on thermal and mechanical properties were investigated. Grafting increased the crystallization rate of PLA, increased the crystallinity and also raised the thermal decomposition temperature. The mechanical properties of PLA-g-IA blended with PLA were also improved.
Crystallization of PLA and PLA-g-IA were investigated during annealing at different annealing temperatures and durations using differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). The rate of crystallization increased after grafting and affected the formation of PLA crystals by increasing the lattice spacing at the (110) plane, suggesting an expanded helical structure of PLA. The crystallinity of PLA-g-IA was also higher than that of neat PLA.  
Although polymer blending offers an attractive route to modify selected polymer properties, it is not always successful without the addition of compatibilizers. Despite the subtle differences in methods to incorporate compatibilizers, development of NTP blends with different polymers, whether a petroleum based polymer, synthetic biodegradable polyester or bioderived compostable polyester, offers material with improved mechanical properties and thermal stability. Water resistance is also improved, however, biodegradability will likely be compromised if the second polymer is not also biodegradable. These blends offer a potentially wider range of commercial NTP grades.

text: Development of Bloodmeal Protein Thermoplastic Blends This study investigated the compatibilization of Novatein® Thermoplastic Protein (NTP) blends with other polymers. NTP was blended with three different types of polymers;a petroleum-based polyolefin, (low-linear density polyethylene, LLDPE); a biodegradable synthetic polyester, (polybutylene succinate, PBS) and a bioderived, compostable polyester, (poly (lactic acid), PLA). It was a relatively straightforward process to produce a compatible blend of LLDPE and NTP using a compatibilizer, regardless of the obvious difference in chemical structure between these polymers. Blending NTP with PBS, on the other hand, was much more challenging. It required two compatibilizers, added at different stages of blending to produce a compatible blend. For blends with PLA, a novel copolymer, itaconic anhydride grafted PLA (PLA-g-IA) was produced to be used as a compatibilizer and initial results suggested that PLA-g-IA may be a successful approach. 
Two different methods of compatibilization pathways were explored: the addition of a graft copolymer based on one of the components (in the case of NTP/LLDPE blends) or using compatibilizers that are not chemically the same as either component (in the case of NTP/PBS blends). Polyethylene grafted maleic anhydride (PE-g-MAH) was added to NTP/LLDPE blends and produced a blend with synergistic mechanical properties (the elongation at break exceeded the raw LLDPE properties). The water resistance of NTP was improved after blending with LLDPE, but it may compromise the compostability of the material. For NTP/PBS blends, two compatibilizers with different functional end-groups were used; these were (poly-2-ethyl-2-oxazoline)(PEOX) and (polymeric diphenyl diisocyanate)(pMDI). Using either of the compatibilizers individually in blends containing 50 % NTP resulted in poor mechanical properties. Compatibilization was accomplished with the addition of both two compatibilizers at different stages of blend preparation; PEOX dissolved in water and added during NTP production, while pMDI was added during injection moulding. This approach led to a tensile strength greater than that of pure PBS (24 MPa compared to 22 MPa). Dissolving PEOX in water improved the dispersion of the NTP phase throughout the PBS matrix via hydrogen bonding between water, PEOX and NTP. The addition of pMDI during injection moulding stabilized and strengthened the interactions between PBS and NTP, thereby leading to a superior blend.  
The compatibility between NTP and LLDPE or NTP and PBS were characterized using thermal and morphological properties as well as water resistance. Two Tgs were obtained for all blends, however, the addition of compatibilizers improved the adhesion between phases, evident from broader and lower height of Tg peaks. The morphology provided evidence of a homogenous dispersion of NTP in LLDPE. In NTP/PBS blends, the fracture mechanism changed from brittle to ductile with the addition of PEOX. Both NTP/LLDPE and NTP/PBS blends showed a phase inversion from a particle- dispersed morphology to a co-continuous morphology at compositions greater than 50% NTP. The water resistance also improved with the addition of LLDPE and PBS.   
Reactive extrusion was used to produce a copolymer, itaconic anhydride grafted poly (lactic acid) (PLA-g-IA). Different initiator (dicumyl peroxide) and monomer (IA) concentrations were used to optimize the degree of grafting. 0.75% was the highest degree of grafting and showed minimal chain scission evident from the polymer’s intrinsic viscosity. The reaction kinetics of grafting and the effect of grafting on thermal and mechanical properties were investigated. Grafting increased the crystallization rate of PLA, increased the crystallinity and also raised the thermal decomposition temperature. The mechanical properties of PLA-g-IA blended with PLA were also improved.
Crystallization of PLA and PLA-g-IA were investigated during annealing at different annealing temperatures and durations using differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). The rate of crystallization increased after grafting and affected the formation of PLA crystals by increasing the lattice spacing at the (110) plane, suggesting an expanded helical structure of PLA. The crystallinity of PLA-g-IA was also higher than that of neat PLA.  
Although polymer blending offers an attractive route to modify selected polymer properties, it is not always successful without the addition of compatibilizers. Despite the subtle differences in methods to incorporate compatibilizers, development of NTP blends with different polymers, whether a petroleum based polymer, synthetic biodegradable polyester or bioderived compostable polyester, offers material with improved mechanical properties and thermal stability. Water resistance is also improved, however, biodegradability will likely be compromised if the second polymer is not also biodegradable. These blends offer a potentially wider range of commercial NTP grades.

year: 2015

title: Verbs in Māori: The problem of definitional criteria

authors: Whaanga, Hēmi

subjects: te reo Māori

abstract: A range of different types of criteria has been applied at different points in the history of the classification of verbs in Māori. These have included syntactic and morphological criteria, semantic criteria and derivational criteria. Unfortunately, these criteria have not always been applied consistently and this has led to considerable disagreement about the classification of verbs in Māori. In this paper, different accounts of verb classification in Māori are critically examined and it is argued that some of the disagreements can be resolved by acknowledging (a) that words in Māori may be assigned to different word classes in different contexts, and (b) that word classes and sub-classes should be determined on the basis of morphological and syntactic criteria with semantic and derivational information playing a role only in so far as they have observable syntactic and/or morphological consequences.

text: Verbs in Māori: The problem of definitional criteria A range of different types of criteria has been applied at different points in the history of the classification of verbs in Māori. These have included syntactic and morphological criteria, semantic criteria and derivational criteria. Unfortunately, these criteria have not always been applied consistently and this has led to considerable disagreement about the classification of verbs in Māori. In this paper, different accounts of verb classification in Māori are critically examined and it is argued that some of the disagreements can be resolved by acknowledging (a) that words in Māori may be assigned to different word classes in different contexts, and (b) that word classes and sub-classes should be determined on the basis of morphological and syntactic criteria with semantic and derivational information playing a role only in so far as they have observable syntactic and/or morphological consequences.

year: 2000-10