European Journal of Science, Innovation and Technology

Case Study Method: Relationship between Fully Softened and Residual Shear Angle and Liquid Limit in Problematic Clay Soil

Kukuh Mahi Sudrajat, Sri Prabandiyani Retno Wardani, Kresno Wikan Sadono — Fri, 26 Dec 2025 00:00:00 +0200

Problem clay soils often experience a significant decrease in shear strength from peak strength to residual strength, which greatly affects slope stability and geotechnical structures. This study examines the empirical relationship between the angle of repose in fully softened and residual conditions and the liquid limit in various types of problem clay soils through a methodological case study approach. This research method is based on the need to comprehend how to operate clay soils under critical conditions, especially on slopes that have experienced movement or are in a remolded condition. The fully softened condition represents the strength of soil that has been loaded to a considerable displacement but has not yet reached the residual condition, while the residual condition represents the minimum strength that can be achieved after a very large displacement. This case study method aims to identify and analyse the mathematical correlation between shear strength parameters (fully softened and residual angles of repose) and the liquid limit as an index of plasticity that can be easily determined in the laboratory. This case study method aims to identify and analyse the mathematical correlation between shear strength parameters (fully softened and residual shear angles) and the liquid limit as an index of plasticity that can be easily determined in the laboratory. The methods used include a comprehensive literature review of previous research, secondary data collection from various geotechnical projects, and statistical analysis to determine trends in the relationship between these parameters. A case study approach was used to validate the empirical correlations found in the literature with local soil conditions. Linear and nonlinear regression analyses were applied to develop prediction equations that can be used in geotechnical engineering practice.

Development of E-Modules Discrete Math Learning Multimedia for Discovery Learning

Fri, 26 Dec 2025 00:00:00 +0200

The purpose of developing learning multimedia for Discrete Mathematics courses based on discovery learning is to provide interactive, in-depth, and interesting learning experiences for students. Through the discovery learning approach, the main goal is to encourage students to be actively involved in the learning process, so that they can develop a deeper understanding of discrete mathematics concepts. Multimedia learning provides opportunities for students to explore these concepts through various media, such as videos, simulations, and direct interaction, which help them internalize the material better. The research subjects were ITB STIKOM Bali students who took the Discrete Mathematics course in the intermediate semester with a population of 35 students. The method used in multimedia development is MDLC (Multimedia Development Life Cycle) which consists of the stages of Concept, Design, Material Collecting, Assembly, Testing and Distribution. This e-module design applies use case diagrams, activity diagrams, sequence diagrams and storyboards. Testing includes blackbox with the results of all functions in the application running well; the second test of user trials using interviews with limited result is that overall students can accept the application well; the third test is a user trial using a Likert scale questionnaire, and the results of the Likert scale score are analyzed using the feasibility percentage formula with a value of 89.6 declared e-modules very feasible to use as discrete mathematics learning media.

Floristic Study of the Herbaceous Vegetation of Wet Lowlands in Aru Territory, Ituri Province (Democratic Republic of Congo)

Wed, 31 Dec 2025 00:00:00 +0200

The study of plant communities was conducted using the Braun-Blanquet phytosociological method, supported by physiognomic, chorological, and numerical approaches. This phytosociological investigation aimed to inventory the biological diversity of wet lowlands in the eastern part of the Aru River watershed and to establish the ecological diagnostics of the surveyed herbaceous vegetation units. The wet lowlands studied constitute part of the water supply feeding the Aru River, one of the numerous tributaries of the Congo Basin in northeastern Democratic Republic of Congo (DRC). These lowlands show limited ecological niche and species diversity due to permanent soil moisture and various anthropogenic activities.

A total of 122 species, belonging to 83 genera, 37 families, and 23 orders, were recorded. These species fall into three cladistic categories: Eudicotyledons (77 species; 63.1%), Monocotyledons (44 species; 36.0%), and Pteridophytes (1 species; 0.8%). As in most savannah regions, pteridophytes are very rare throughout Aru Territory.

The floristic inventory was carried out in 10 phytocoenoses, including communities dominated by: Cyperus distans L.F. var. distans, Hyparrhenia subplumosa, Polygonum pulchrum Blume, Leersia hexandra Sw., Triumfetta cordifolia A. Rich var. cordifolia, Vossia cuspidata (Roxb.) Griff., Pennisetum purpureum K. Schum., Cyperus papyrus L. subsp. percamentus, and Ludwigia abyssinica A. Rich.

The Poaceae family is the most diverse (24 species), although the physiognomy of the vegetation is shaped mainly by Cyperaceae, dominated by Cyperus distans var. distans. The environment is favorable to geophytes and hemicryptophytes.

Anemochory is the predominant dispersal mode, with sclerochorous and sporochores being frequent. The phytogeographical spectrum is dominated by species with very wide distributions, with pantropical species being the most represented.

A perennial species of Melastomataceae, Centradenia inaequilateralis (Schltdl. & Cham.), was collected in the humid station as an indigenous species. Originally from Mexico, it is now introduced in tropical and subtropical regions, including Réunion Island, where it is cultivated in botanical gardens.

Floristic homogeneity was observed between some groupings, with a Sorensen coefficient of 60%, particularly between the mixed grouping (Triumfetta cordifolia var. cordifolia + Cyperus distans var. distans) and the Pennisetum purpureum community. Some phytocoenoses exhibited very low species diversity indexes and shared no species in common.

Study of the Growth Parameters of Twenty-Nine Sweet Potato Cultivars [Ipomoea Batatas (L.) Lam., 1793]: Collections in the Various Territories of Maniema Province, DR Congo

Wed, 31 Dec 2025 00:00:00 +0200

The main objective of this study was to evaluate the growth performance of 29 sweet potato cultivars [(Ipomoea batatas (L.) Lam., 1793] collected from different territories in Maniema Province. Twenty-nine cultivars were collected in five territories of Maniema province and the city of Kindu. To achieve this, we used an elongated plot design composed of simple rows. The results obtained showed that: the highest number of lobes was observed in cultivar C20 with eight lobes; the longest petiole was observed in cultivar C2 with 28.17 cm; the largest dimensions of the spreading leaves were recorded in cultivars C17 and C10 with 23.67 cm and 23.33 cm respectively; for the length of the main stem, the maximum values were recorded in cultivar C24 with 384.00 cm, followed by cultivar C3 with 330.00 cm; the shortest internodes were noted in cultivars C28 and C21 with 2.33 cm and 2.50 cm respectively. Hierarchical ascending classification (HAC) made it possible to establish a dendrogram illustrating the structuring of sweet potato cultivars into five distinct groups, defined on the basis of their growth characteristics, and another dendrogram illustrating the structuring of sweet potato cultivars into four different groups based on their morphological characteristics of the aerial parts of the plant.

Effects of Cutting Height on the Recovery of Some Forage Grasses under Cultivation in Kindu, DRC

Wed, 31 Dec 2025 00:00:00 +0200

This article analyzes the effects of cutting height on the recovery of some forage grasses under cultivation in Kindu, (DRC). The few forage grasses concerned are Pennisetum purpureum, Panicum maximum, Hyparrhenia diplandra and Paspalum chevalierii. The effects of cutting height on the regrowth of several grasses were studied in a separate experimental setup, randomized complete blocks comprising four treatments and four replicates. Each 4m x 2.5m plot, i.e. an area of 10 m², received 40 stumps and cuttings installed at 0.5m x 0.5m spacing, i.e. 0.25 m². These plots were separated by paths 2 m wide each. Thus, overall, the system consisted of 640 stump fragments, cuttings and the total field area was 1612 m². The results obtained can be summarized as follows. Better recovery was observed in the forage species Paspalum chevalierii, which recovered well at all cutting heights, followed by Panicum maximum for cutting heights of 5, 10 and 15 cm; Hypparhenia diplandra comes in third, while Pennisetum purpureum closes the way. Regarding the regrowth rate, 10 and 15 cm heights proved more effective for species of Panicum maximum, Paspalum chevalierii and Hypparhenia diplandra, which behaved well.